Thanks all. I'm relatively local (Woking) so either get the train to Gomshall or drive to Holmbury YH. I have a reasonable little loop worked out, based heavily on the one in the Trail Guide:
Holmbury YH, right from carpark, between reservoirs, fire road climb to top of Holmbury.
Parklife then Telegraph Road (and have found the off camber parallel route.On Telegraph right at the fork near the end for the extra singletrack that spits you onto another bridleway/fire road.
Onto Horsham Road then left onto Pasture Wood Road and onto Greensand Way, climb to top of Leith Hill.
Down the other side, past the cricket pitch, off to the left along the singletrack that spits you onto the climb by Summer Lightning.
Ride all of Summer Lightning, down to the road and onto the A25. Ride roads back to Holmbury YH.
It's not a bad route, but I'd like some more options and variety. I'm also sure there's a much more interesting way to get back than spinning along the A25, without covering the same ground. There are also a few pics of some North Shore on the Nirvana site that I'd love to find (Mangrove Alley), and the jumps they show on Reformation.
I'll have to start saying hello to people when out and about (probably when I have the new Five built – my ratty Rockhopper creaks and groans like crazy) but I don't want to slow anyone down (my climbing pace is pretty poor atm!). Nothing beats local knowledge (I was an Epping Forest local for many years and knew tons of secret stuff).