Seruzawa,
The myth that the British labor government a much to do with the death of the British motorcycle industry has been repeated so many time people just assume it is true. Take a look at Burt Hopwood's book "What Ever Happened To The British Motorcycle Industry". Once you get past Mr. Hopwood's tendency to vilify people, specifically Edward Turner, and excuse his own mistakes you'll find some interesting things.
The first one is that by the time the Labor government came to power it was much to late for anything to save the industry. Not even going into what killed all the others (James, Matchless, AJS, etc.) and lost the lightweights battles take a look at the prototype three cylinder Hopwood and Doug Hele built in '65 (pages 214 to 217) the amazingly ugly 1969 triple (page 229) and the 1971 version that finally sold well (page 230). Anybody want to guess how well the prototype would have sold in '66 without the Honda CB750 or Kawasaki 500 on the market for three and two years respectively?
The British killed themselves, government stupidity (Conservative and Labor) provided a little help but saying the government had a role is like saying the person who made the rope has a role when people hang themselves. Specifically blaming Labor would be like blaming the person who finds the body, if they'd just gotten there sooner he might have lived. The British just proved that capitalism works, a group of companies didn't make what people wanted, another group did. The former failed and the later thrived.
SlowBear