Hi
@3-speeder
Yes, it's a second pattern BSA parabike, almost certainly 1943. And like all of them it has good and bad points, which may, or may not, be important to the buyer.
I don't do valuations, sorry, too much grief in the past, but you can look up past sales on CABE to get an idea.
Good points on this bike : Original 2nd pattern frame, Original pedals, pedal arms with the correct slightly later extended boss, chainwheel.
Bad points: (read: expensive to find originals), wrong saddle, wrong front and rear brake callipers. Repainted (missing decals).
Unknowns: Can't see the handlebars, grips, T bar for loosening the handlebars. Unable to verify wheels and hubs are correct (though they look OK). Brake levers. Tires unlikely to be correct. Can't check general function, including the folding mechanisms.
The Bergan frame strapped to the bike is also a good feature, and can be expensive. But these were also produced post war, impossible to tell from the photos.
Don't know what the metal thing clamped to the rear left frame is.
Overall, a good, average condition bike, which looks to be in usable condition as it is, with the advantage of the original pedals (often replaced), but other missing parts could cost several hundred dollars and some time to replace.
Best Regards,
Adrian