It's certainly motivated me to give it a bit of TLC.
The police suggested they likely stole it initially with intentions of selling it, but then probably chose to dump it after realising it was quite a specialist bike, thus being quite easy to spot if stolen.
They've told me a few more details now - apparently it was dumped in bushes near a big estate called Swan Court approximately 1 or 2 miles away, so not even that far from home.
Interestingly they also said that its a very low crime area for bicycles - apparently only four bikes (including my own) have been stolen since 2009.
Anyway, thanks again for all your help and kind words. Maybe I'll pop some pictures up of it down the line once I give it a clean up.