UK Help with speeding ticket defence?

Tell the Judge your story, as you just told us. But it would really help if you could get some evidence to support your story - like a statement from the previous owner supporting your statement about the speedometer, and you just buying the bike. It would also help if you could support your statement about the bike being stolen, otherwise they would wonder why you didn't have a shop look at the speedometer and support your statement about it being so far off.