Never caught the Vincent fever. When stuff is too old and too agricultural even for me, you know it is no good
A mate of mine has two of them. One he rides, the other he races. The racebike engine was rebuilt by the Horner brothers, of Irving -Vincent fame. Prolly has $200K+ tied up in the two machines, ...but then he also has a square case 900SS, a mint RC30, an MV F4i, a '47 Triumph 500 he restored himself, a Ducati 998, an S1000RR, a Harley of some sort, a KTM1190R, and about 6 or 8 dirtbikes. All that and he's a really nice bloke. No bullshit, no airs and graces, and really, really, fucken fast.
Outcome of a quick search, it looks like the switched from 2 small drum brakes to one large one in latter years, could be wrong as the photos could be of modified ones
All Vincents had cantilever rear ends and girder forks. The pic you've used is of an Egli-Vincent; Vincent engine/Egli frame, which has a twin-shock rear end and telescopic forks. Also only worth about half the price of an original.