Found it at last ... it's a De Joux GT. 2 or 3 were made by Ferris de Joux between 1958 and 1960. The one pictured had a Standard Vanguard powertrain and a shortened TR4 chassis and was known as the Vanguard GT. The other survivor was a 2+2 with a spaceframe chassis possibly by Buckler NZ and a Vauxhall engine later replaced by a Holden V8 , . The third is rumoured to be Jaguar powered.