In reply to Heike:
> Difficult to know, everything that comes his way and I don't object to! So, he plays a lot of Minecraft (and similar games), flight simulators, Steep, Call of Duty (against my wishes), car racing games etc
Ok, well in that case, CoD will probably be a bit of a stretch on that machine. Flight sims will work, but you'll have to turn the settings down a lot. Racing games, again with low settings, probably ok.
Minecraft is fine, it's pretty low resource. Steep should be fine.
A 'good' gaming laptop will cost £1000 odd. For the money what you're looking at is ok, but it will struggle with newer games. If he's already got a console, then I'd strongly suggest that he games on that and just uses the laptop for programming etc.
As others have mentioned the 'best' option is to have him build one himself. If he's into programming then it's a good idea to have a baseline of how computers work. While you won't get a good gaming rig for £650, it'll be better than the laptop and you can upgrade it.