Entry level bike for about 600 quid. (hardtail)

If only there was some sort of information service, possibly online, where a variety of shops could be searched for details of products you're considering buying. Oh, wait… 😉

More seriously, how about one of the entry-level models from Specialized or Giant? The top Hardrock comes in under-budget, should be solid with good warranty and after-sales rep.

He was looking at one the ghost bikes, but it looks a bit racey.

Try second hand – get a much better spec – I picked up a nearly new built up cove hj for 500 and its done (doing) me proud so far

take a look at the KHS stuff, lot of bike for the money.
M8 of a m8 bought one last year (i helped set it up for him), very nice and he's had no problems

http://www.khsbikes.co.uk/bikes