Hi James,
Whilst being in need of some TLC, this bike looks reasonably original - the main exceptions being : 1. the seat, 2. the silencers, 3. the voltage regulator (on the front of the toolbox), and 4. that awful rear stand that must seriously compromise the handling. As was common on Mk3 machines, the frame has had several repairs carried out around the rear bottom lugs (some of which look a bit suspect).
Obviously, the bike will need a thorough check over before being used, but most of the original parts are there, and look to be sound.
With regard to the colour - Douglas would supply bikes in non-standard colours to special order, but this one looks to have been an original blue/black machine that has had the mudguards re-sprayed red.
If you do decide to buy this bike, get back on to this forum - you will get a lot of help from the members, and also suggestions on modifications that overcome some of the original shortcomings.
Best of luck,
Regards,
Eddie.