This is my first post so please be gentle

Travel measured is about 10mm, should this be alot more or is it about right?
Ok here's the history:-
I've only owned it for about 3 weeks before that I borrowed it for the last 8 years and used it for camping at silverstone for F1! It had the clutch and slave cylinder replaced 11 months ago. Clutch worked fine then suddenly failed at the weekend, cannot engage gears unless the revs are correct. When engine off and stationary all gears can be selected just not when the engine is running. Checked the master cylinder and there is a little bit of fluid on the rubber seal. So I'm guessing that the master cylinder seal has a leak and let some air in (well fingers crossed that's what it is).
I'm going bleed it tonight and see if it improves.
Any other thoughts on what this could be? There were no funny noises prior to the failure, the only thing was that the clutch was pressed in for more that 30 seconds whilst trying to pull out on on a busy roundabout.
Thanks for your help
GP
