I'd start it off lower. From what I've read, Fullers pitch the yeast at 17C/18C then raise to 20C. Then (iirc) when fermentation is over crash it down and hold it there for a bit while the yeast cleans up
Sorry to pester you again but hey, that's what forums are for, right?! Ok so it was fermenting at 5am today so it got going in less than 17 hours. It's chugging away steadily now but at about half the speed of CML stuff. Now I know that is notoriously fast but how should the Fuller's stuff do in comparison? It's at bang on 20C as you suggested. Cheers!