Well, it's all academic now, bike is sold . Finally got through to John at Williams Motorcycles this lunchtime (had tried yesterday lunchtime but couldn't get through). Bike was sold yesterday afternoon. Anyway, had a long chat with John, and he's promised to let me know if they get another lowered one in. He did say that it is rare. Turns out it wasn't an ex-demo - ebay listing was incorrect.
Still, somebody out there will have a big grin on their face, so I guess I should be happy for them