Sinclair C5 with Sinclair claiming that he had found "very big" levels of interest. Hoover were sufficiently persuaded to allow Sinclair to divert 10 of their employees to modify C5s for overseas export. The bid to sell the C5 abroad failed; the Dutch National Transport Service told Sinclair that the C5 was not suitable for Dutch roads without improvements to its braking system, the addition of more reflectors, and the inclusion of the High-Vis Mast as part of the basic package. Most of the other ten countries that Sinclair inquired of demanded similar changes. The C5's reputation received a further battering when
Clive Sinclair left school at the age of 18 and instead he sold miniature electronic kits by mail order to the hobby market. Sinclair's Micro Kit was formalised in an exercise book dated 19 June 1958 three weeks before his A-levels. Sinclair drew a radio circuit, Model Mark I, with a components list: cost per set 9/11 (49½p), plus coloured wire and solder, nuts and bolts, plus celluloid chassis (drilled) for nine shillings (45p). Also in the book are advertisement rates for "Radio Constructor" (9d (3¾p)/word, minimum 6/- (30p)) and "Practical Wireless" (5/6 (27½p) per line or part line). Sinclair estimated producing