Well the Brits lost their way there for a while with the "bathtub" Triumph and even the Vincent "black prince" model with full obese bodywork. The problem was they didn't realize that they were right in the first place to be going with minimal weight and other nonsense added to a good basic design of engine and frame.
It happened again in the seventies when they were running scared of the Japanese juggernaut . They realized too late that they had been resting on their laurels way too long and thought they had to start "modernizing" their traditional models. As a result, they started making ill advised and short sighted cosmetic changes to the British lineup which has made the early seventies models unfortunate orphans in the view of collectors . (except for Nortons which continued to get better with no cosmetic changes)
What was needed .of course, was some fundamental engineering updates to engines and running gear which had been coasting along since WW2 on their undeniable c qaadvantages at that time of high horsepower from light small engines and decent handling frames and tires. (Look up Triumph Speed Twin}. The Japanese showed the way to modern motorcycles and it was too late for the first gen Brit bike manufacturers. Not until John Bloor came along and brought Triumph into the new millennium with modern designs and high build quality did British motorcycle manufacturers get a new lease on life.
I love my old Bonneville as a good example of the beautiful, but flawed, Brit bike of the '60s that combined undeniable design beauty with crude build quality and questionable pre-war engineering. It's interesting to think of what might have been if the engineering and manufacturing skills of the Japanese had been applied in Britain in the '50s and '60s when it really mattered for Triumph, Norton and BSA.
End of rant
2004 Rebel 250, 2003 BMW K1200GT (roadburner), 2004 BMW R1200GS(all purpose),
1973 Norton Interstate (in a box in the basement)
1968 Triumph Bonneville