tokai, edwards etc. would be an excellent choice. i have an edwards les paul, it's very nice (though, to me anyway, it's more of a rock guitar than metal). i have an 80s tokai strat which is also great. only problem with edwards is that with the pound not doing so well, they aren't as good value as they used to be... richtone seems to sell some tokai MIJ LPs for £500, but i haven't tried those exact models...
if you're after something more metal, how about an ibanez rga121? made in japan, mahogany body, thin neck, no trem. it seems to tick most of your boxes, but you'd need to try one, and also the pickups could do with being upgraded. it might be slightly over budget, too (like £530, or £550, something like that).