Damm! That looks to be a P11 about 1965!
Was it for sale? Bought one new - had it for a few years - was stolen.
Sure like to have another - they are hen's teeth hard to find.
I have a Matchless G80CS like the one in the first post. Mine is in boxes but is sloooowly coming together.
The Norton engined Matchless twin is a G15CS. The P11 had a frame made from Reynolds 531 tubing and is the same as the Matchless G85CS which had the G80CS engine in it. The P11 makes hens teeth look common!