1973 Gilbern Invader MkIV prototype

1973 Gilbern Invader MkIV prototype

By 1973, Gilbern had graduated from kit cars and was eying promising new markets with a big new coupé. Fate had other ideas – but today we drive the sole Invader MkIV prototype.


Photography GUS GREGORY

The Gilbern that might have pulled over motorway speeders

Welsh Rarebit

Driving the last-gasp Gilbern Invader MkIV once offered to the police

Having owned several Gilberns in the past, I know the marque well, but this one is different, it’s unique. At first glance you could easily mistake it for a regular production Invader MkIII, but take in the proportions and it soon becomes obvious that this car is more than that. Compared to a MkIII it’s actually 12 inches longer from the B-pillar to the rear bumper. The rear side windows are longer and so is the boot lid. This is the only completed Gilbern Invader MkIV of two partially-built prototypes – the other has never surfaced.

1973 Gilbern Invader MkIV prototype

I open the door and peer inside. The front compartment is basically similar to any MkIII but the rear passenger area is considerably more spacious. I undo the safety latch to the front seat squab and climb into the back. The two well-upholstered rear passenger seats are just the same as in the MkIII, comfortable and laterally supportive, but with its long wheelbase this MkVI’s rear quarters are different from the close-coupled MkIII – there is legroom in abundance.

1973 Gilbern Invader MkIV prototype

Negotiating the relatively wide sill, I transfer to the front, dropping into the comfortable and laterally supportive driver’s seat. The dash layout is no ergonomic triumph but everything is within easy reach, and having spent considerable time driving a MkIII I feel pretty much at home. Gilberns were always well fitted out with every possible instrument and switch a driver would ever need, and all are easy to view. Within the elegant walnut veneer dash before me are a matching 140mph speedometer and 8000rpm tachometer.

I twist the key, press the starter button, and the modified 3.1 litre Ford Essex V6 fires immediately, the exhaust note settling into an urgent sporting burble. The slightest tickle of the throttle sends the tachometer needle spooling around the dial to the musical accompaniment of the twin exhaust pipes exiting the rear end in double outlets. They emit a deep but unobtrusive burble when trickling through town, but once freed and under hard acceleration, the note rises to a refined but deep growl as the engine spins through four thousand and onwards.

1973 Gilbern Invader MkIV prototype - engine

Being more familiar with the four-speed Ford Zodiac gearbox fitted to the MkIII, which had overdrive on third and fourth, I find the five-speed Ford T9 unit that this Gilbern now sports is particularly well suited to the performance of the car; it’s also lighter. The ratios seemed to be ideally spaced, there’s no lag in urge when changing up from second to third as there is on the Zodiac gearbox. There is colossal torque available from the Essex V6 and fourth gear is particularly impressive. Then just snick the short lever forward and across into the fifth ratio for swift, quiet, and utterly unstressed progress.

Although at slow speeds the tuned V6 is a tad cammy, any lumpiness clears easily and accelerating through the gears is particularly impressive. Drop the clutch suddenly and the rear 185/70X13-clad Dunlop alloy wheels spin readily, the rubber squeals and screeches and the Gilbern rockets forwards. The benefit of the Ford T9 is clear; I don’t know the ratios but they are certainly well-spaced. The servo-assisted discs at the front and drums at the rear slow the car well, without any hint of fade in hard use. The engine has been dynamometer-tested and produces 140bhp and 175lb ft at the rear wheels. But I’m wondering what effect that longer wheelbase will have on the drivability of the car compared to a MkIII.

1973 Gilbern Invader MkIV prototype - dashboard

After entering a tight right-hander I give it a foot-full of throttle; even though grip is impressive, there’s significant roll and I can sense the back wanting to let go and come around at an earlier point than I would have expected from a MkIII – certainly not what I’d predict with the lengthened wheelbase. The spring rates are unchanged from the MkIII – stiffer springs would probably help; if it were mine I’d fit stiffer ones and screw up the adjustable Spax dampers. The prototype’s ride is certainly comfortable enough, so I don’t think the drive would suffer noticeably from making such changes.

‘There is colossal torque available; fourth gear is particularly impressive’

The unassisted rack-and-pinion steering system is as found in a Ford Cortina MkIII. The turning circle of 33ft is particularly handy and although it’s a tad heavy at parking speeds, that disappears once on the move. It is precise with plenty of feedback through the wheel; entering a corner quickly, I can feel it loading up and telling me exactly what is going on up front all the time. The Gilbern likes to be driven; show it a firm hand and it will sweep through corners smoothly without any unruly twitching, or the need to saw away at the wheel. If you do make a mistake and enter a corner too quickly on a trailing throttle, there also seems less tendency to understeer, simply get back on the throttle and the car remains comfortably planted.

1973 Gilbern Invader MkIV prototype

Gilbern had planned to launch the Invader MkIV at the 1973 British Motor Show at Earls Court. The main criticism of the otherwise-successful Invader MkIII was lack of space in the rear compartment, and the new version addressed that problem. It would provide greater boot space, considerably more legroom and genuine four-seater comfort – a true executive express. It was also intended that an estate version would follow, in an attempt to follow the success of the MkII estate.

‘The officer jumped in next to Hathaway, who was speechless’

Shortly after Christmas in 1972, Gilbern delivered the prototype stretched MkIII Invader chassis and GRP body to A Cars of Wiltshire, which was charged with producing a mould for what would become the productionised MkIV. However, Gilbern was in financial difficulties and well before the motor show, it ceased trading. Work on the prototype MkIV halted, Gilbern did not exhibit at the show and the unique long-wheelbase Invader MkIV body and chassis were left languishing at the A Cars works.

Over time, the remains of the MkIV passed through the hands of various folk, all intending to eventually complete the build but none succeeding. From Gilbern insurance brokers Alan & Gwyneth Casey, it passed to enthusiast Bev Fawkes before eventually ending up with Gilbern Owners’ Club spares secretary, Peter Thomas. The fate of the second chassis is unknown, but it’s presumed destroyed.

Enter Frank Robinson, an Invader MkII owner and member of the GOC. Frank used to work as a production engineer at Rolls- Royce in the same facility as Richard Bonnie, then-secretary of the GOC, so knew the story behind the MkIV. It had always intrigued him but at that time, being newly married, he wasn’t in a position to either buy or spend time working on such a project.

1973 Gilbern Invader MkIV prototype

In 2005 however, Frank met Peter Thomas, the GOC spare parts secretary at the time, who had the car in his hangar with all the other club spares. Frank asked Peter if he would consider selling it, but Peter declined because he was planning to work on the car himself. A year later Peter called Frank asking if he was still interested; Frank was. They agreed on £1500, which would include the spares required to complete the project.

Frank explains, ‘The car came to me as a bare GRP ’shell, plus the original lengthened rolling chassis with both axles and steering gear fitted. Also among the bits and pieces were the inner flooring panels, which had not yet been properly finished, so had never been fitted. Theoretically it should have been ready to fit but obviously they were made in a hurry from standard MkIII parts so I had to alter them to compensate for the extra length. When I eventually fitted the body to the chassis, I had to finish all those panels before they could be fitted. When you look closely at the rear wings, the roof and the bootlid, it is quite clear where Gilbern stitched the lengthened rear GRP sections. To obviate flexing, I placed strengthening steel square tubes within the roof structure. One runs across the car from the top of each B-pillar, another runs each side along the length of the roof, then down the A-pillar where it is welded to the chassis at the bottom. The outriggers are also boxed in to provide extra rigidity.’

The MkIV only made it to the rolling chassis/body stage and never received a drivetrain but it was set to receive a Ford Essex V6, so Frank obtained a 3.1-litre unit stripped and rebuilt by NTS Automotive of Reading. It has a fully lightened and balanced bottom end, alloy timing gear, high-pressure oil pump, oil cooler, gas-flowed cylinder heads, Weber 40 DFAV downdraught carburettor, Gilbern tubular manifolds, electronic ignition and a Kent ‘fast road’ camshaft. The five-speed T9 gearbox it has been mated to has a ‘quick-shift’ change, driving through a heavy-duty clutch with an alloy bell-housing, while the propshaft is a lengthened Ford Escort item. Frank explains, ‘I fitted a T9 gearbox because I felt that the Zodiac four-speed was getting long in the tooth by the time the MkIV was conceived so it was almost inevitable the T9 would have been offered eventually, especially as it was lighter.’

Inside the car, the GRP inner rear wheelarches have been modified from the original MkIII to match the extra length at the rear compartment, so that they helpfully double up as comfortable armrests for the rear passengers. The back section of the transmission tunnel is also slightly lower and less intrusive than it is in a MkIII. Frank was able to produce all the doorcards and trim them himself; the seats however, which are of course the same as those found in a standard Invader MkIII, were done professionally.

There were several unsuccessful attempts to relaunch the Gilbern company. According to the book by Phil Ivimey and Martyn Morgan-Jones, Gilbern – A Dragon’s Tale, one plan was to rename the MkIV the ‘Invader Prince’; accordingly Frank has mounted a chromium Prince logo to the nearside rear panel. By the time Frank finished the car, both Gilbern founders, Giles Smith and Bernard Friese, had died. As a homage to them, Frank had the badges for the bonnet, rear panel and front wing flanks made up in black and gold instead of the usual red and green. In 2012, after seven years, the car was finally up and running; in gleaming black with a gold coachline, the car looks almost limo-like. Less like a sports saloon, more a sporting executive express. Although the MkIV was together in time for Frank’s daughter’s wedding, he says that it took another three years before the car was finally finished to his satisfaction and various minor niggling problems had been ironed out.

It is particularly sad that the Gilbern Invader MkIV did not enter production; it might have saved the company. GOC archivist Philip Ivimey recalls an intriguing story that Cardiff Gilbern dealer Donald Snow relayed to him in the Nineties. ‘In the summer of 1972, he and Gary Hathaway [driver of the Gilbern works rally car] had driven a MkIII to a company at Dallington. They came off the M6, drove down the A5 and easily and tidily passed a complete line of cars.

‘The next thing they knew, there was a flashing blue light in the mirror and a police officer eventually caught up and stopped them. The officer asked Donald if he owned the car; he said yes. Then he asked if Donald was aware of the speed limits on motorways, saying, “We have been trying to catch you for 12 miles and your speed has not dropped below 105mph.” Donald apologised and said he was only cruising. “Cruising?!” the policeman said. “What car is this anyway?”

‘Donald explained that it was in fact the only car made in Wales. The copper wanted to know all about it, asked what engine was in it and various other details; he’d thought that it might have been something Italian. Trying to get himself out of a problematic situation Donald offered, “We are the dealers and distributors for Gilbern in Wales and we’d actually like to introduce the Gilbern to the police. Don’t think I’m trying to be funny – I accept that you’ve got to make a report. But since you’ve stopped me, would you like to drive the car yourself and then tell me what you think of it?”

‘To Donald’s relief he agreed and jumped in next to Hathaway, who was speechless. Donald joined the other officer in the police Jaguar XJ6 and off they went in convoy. With 110mph on the Jaguar speedometer, the Gilbern was simply running away. Donald said that when both cars stopped, the officer came back and said, “If you’d been trying, no way would we have caught you. Christ, what a car. Look Mr Snow, we really do have to put in a report, I’ll put you down as doing between 78 and 83mph.” ‘“OK, thanks,” Donald said, “But what do you think of the car?” ‘The officer replied, “Well, if there was a little more room inside the car I think it would be marvellous,” and wrote down the phone number of the Midlands traffic superintendent. “Give him a ring. Don’t tell him I sent you, but I’m sure he’ll be happy to give you an interview and test your car. What’s more, he will have a lot more people thoroughly test it.”

‘Donald said that eventually he spent a whole day with the police while they thrashed the MkIII up and down the M1. They simply could not get over the performance; their only issue was that there wasn’t quite enough room inside, and they expressed the desire for more headroom. Then Donald told them there was a long-wheelbase MkIV version in development and that the company could have a running prototype ready very shortly. He explained that two long-wheelbase chassis had already been made, one of them being a rolling unit already at A Cars of Salisbury, which was taking a mould of the body so the model was ready for production. He said the superintendent’s parting words were, “Well OK then, when you’ve got one ready, give me a ring and bring it up here right away.”’

Less than one month later in July 1973, Gilbern went into receivership. Rescue and success were so near and yet so far. Gilberns are fundamentally good, reliable, high-performance classics, sadly somewhat overlooked or underrated. The Invader MkIV’s extra cabin space and huge boot would have made it even more attractive as a sporting machine for families with two children of any age – perhaps also a pair of traffic officers with a boot full of equipment and the driving proficiency to catch ne’er-do-wells and accommodate them in that spacious rear cabin. If only the company had clung on that bit longer…

Torque from Essex V6 gives commanding road performance 8k rpm tacho ambitious for an Essex V6; 5750 redline more realistic.

Rear wheelarch intrusions turned into armrest ‘features’.

Black and gold badge a later addition to honour founders.

Prototypical bootlid extension looks ‘honest’…

Big GRP V6 coupé would have given Gilbern a quiet niche Typical Gilbern abundance of instrumentation MkIV’s mooted ‘Prince’ badge

TECHNICAL DATA 1973 Gilbern Invader MkIV prototype

  • Engine 3093cc Ford Essex V6, ohv, Weber 40DFAV twin-choke carb
  • Max Power 140bhp @ 5500rpm
  • Max Torque 175lb ft @ 3500rpm
  • Transmission Ford T9 five-speed manual, rear-wheel drive
  • Steering Rack and pinion
  • Suspension Front: independent double wishbones, coil springs, adjustable Spax dampers, anti-roll bar. Rear: live axle, located by twin parallel trailing radius arms, Panhard rod, coil springs, adjustable Spax dampers
  • Brakes Servo discs front, drums rear
  • Performance Top speed: 130mph+
  • Acceleration 0-60mph: 7.5 sec
  • Weight Approx. 1225kg
  • Cost new n/a
  • Value now approx £20,000

Two Invader MkIV chassis were made; only this one was ever completed.

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