I don't know why but I checked my brake lights this morning - I know I should do it before every ride but who does. When I applied the brakes brake lights did not come on but there was a large light, a bit like a motorway fog warning light, on all the time. I removed the micro switch and thatlight went out and the brake lights came on when I operated the micro switch by hand.
What must have happened is, when I removed the brake lever a while ago a small push rod, only 2 or 3 mm long, must have fallen out. This allowed the micro switch to go to the closed, brake lights off, position. I am making a wood template to see if I get the right length before I can buy a correct replacement - if available. I must have been riding a couple of hundred miles without brake lights, not to be recommended so beware and observant. But I still love the bike.