I'm in contact with one of the lucky owner of one of the only 4 Coldwell built.
All the following pictures and info are courtesy of Don Turner.
The puzzle's car was built by him from parts supplied by Bill Needham and campaigned it it the 1972 BARC hillclimb championship.
His car is featured in Booij's book "Maximum Mini" . He swapped it for an Alfa 1300 junior but the previous owner used it for auto crossing!
One of the 4 cars was found in Sheffield a few years ago. Another one is in America, and belongs to a chap in Yarm in Northumberland and Bill's prototype went to Singapore where it was crashed.
The engine of the car featured here was one of Bill's. It was a 1071 Cooper S bored to 1120 and fitted with a BMC super sprint cam and 45 Weber, the suspension was based on the Brabham BT21 single seat racer,as John Buxton's BT21 was in the garage at the time.
Bill Needham also had dealings with the Biota. John Houghton had some cars built by Bill and then John went on his own.
Pic#1,2 and 3 ( car #166) show Bill Needham and the prototype. Don took these pics at Silverstone in 1969. He was having a look at it prior to purchasing one. The engine in this was the 1120cc one that He subsequently purchased off Bill and put in his.
Pic#4 and 5 (car #106) show the GT at Silverstone and are older pics with the Mk1 front, from Bill Needham collection. The engine is again the 1120cc engine that went into Don's car.
Pic#6, 7 and 8 show Don's car under construction. The front brakes are drums as it was first set up with minifins and mini wheels from mamba that came from Bills prototype. It only was used a couple of times like this before it was changed to Triumph Herald uprights and disc brakes with 7.5" front and 10" rear Minilights as seen in all the other photos (including the pics in Maximum Mini)
Pic#9 and 10 show Don's car racing.