I didn't like the options for holding the rotor (I had the back wheel out so couldn't use the rear brake/in gear) so I searched for a rotor holding tool. I couldn't find any outside the U.S. then realised we stock something very similar at work a "clutch holding tool" for scooters. It worked perfectly!
Here's our supplier : http://www.pedparts.co.uk/product/670/s ... lding-tool
Or you can phone where I work Midland Scooter Centre on 0115 939 2713 (I'm only there on Saturdays now)

I'm not trying to plug ether of those business's so feel free to go wherever you want, just spreading he word there is a affordable tool that does the job with no damage to the rotor! Actually looks like what's in the Haynes manual too so i presume they're really the same tool.

I'd buy that right now if I didn't already have one made up as per the Haynes, or if I had to buy any bits to make one.
That looks like a real decent tool for £15.

Well worth the money for that tool...

If you phone on a Saturday and ask for Ben I may be able to give slight discount. One of the pins is the exact right size and the other is slightly too small, worked perfectly though and didn't slip so was very chuffed I wasn't having to jam anything or risk twisting the crank!