Willem Boterman was Caterham agent from 1973. The car was to narrow [ seat width ] for the dutch law. so the original seven S3 was modified by Willem, to get the seats wider. the chassis was widened and made longer [wheelbase 230 cm], bootspace was made bigger, rear body and wings modified. all in cooperation with caterham. a new superseven 3B was born.[called; "boterman"] the chassis was made in an own jig, by arch motors in huntingdon UK. the project was ready in 1976 and 22 kits sold. 2 kits to england, and 4 to germany [knitter] soon to be copied by a french firm, later by others, like VM and rush, etc. in 1978 willem moved to england, and sold the project to joop donkervoort. he started to call it 3D, and later called it Donkervoort, to avoid agreed royalties. in england, willem started to manufacture the KOUGAR kitcar. moved back to holland in 1981,and was asked by caterham to be their agent again. needed type approval, which took 2 years.[the law was to be changed] willem sold caterhams till 1989. after this started importing the VM for 2 years, till 1991. sold about 40 VM's. in 1991 the production of his own seven started, called "BARTAN 7", based on ford mechanics with zetec engine. did all the type approval, including emission and sold about 15 kits. also developed a BARTAN R, based on renault mechanics, with 5 cil volvo/renault engine in front and UN1 transaxle in the rear. but typeapprovel rules changed, so no commercial production anymore!