When I first got a Velocette 500 in 1969 it was keyless. The ignition was by magneto and there was no key - if I kicked it, it would start. If somebody else kicked it, it wouldn't. Usually.
Fit a race cap, easiest option, I bought mine from the states, had pretty poor fitting instructions but I sent a full typed instruction to him and he said he was going to use it in the future. Best thing I ever did, key is then tucked away safely, being kept dry, and always on your person. Search on fleabay should find it.