I have a box full of plastic handlebar sleeves from the '50s. Made by Dare. You warm them in hot water and slide them on, shrinking to fit. If they are going on to drop bars, you cut them and apply them, in order, around the brake levers, on to the end of the bars. They are one of the few items i have in bulk, but have never ever sold one! It seems to me that they would be very useful for the restoration of a British lightweight from the 50s, especially a TT bike.
Regards
Martin Coopland