I have found over the years with classic cars and bikes that most pattern parts are pretty poor, they are either made from poor quality materials or fit poorly or both.
It is usually better, where possible, to try and find an original and refurbish it than use a replacement.
I spect last night hiding a modern brake switch on an old bike in parallel to the new pattern switch because the contact strip inside the new switch was 1/3 of the length of the original. The switch is very visible and distinctive so it is in and wired in place but has another hidden switch actually providing 2/3 of the brake light switching.
How difficult would it be to make these things work properly, it took hours playing with it before finally giving up and just using it as a prop.
Anyway, still to work out what is good and bad in Britpart, got that to look forwards to in my own restoration