I don't know but I've heard Wolf Armouries aren't great? That and Pro Airsoft Supplies are the only ones I know in / around London, PAS are great by the way, would definitely recommend them.
I'd go to PAS any day of the week over Wolf Armouries. There's 2 threads on the places to buy board filled mostly with people with bad experiences with them(Wolf Armouries that is), whilst I don't think I've ever heard a bad word against PAS.
WA are generally OK depending on what mood they're in but I'd go for PAS as my first choice. If you're not too far from Romford you've also got the guys at Airsoft Zone who are also pretty good.
i was in wolf armouries on Friday, (21/03/14), and the guys were great good advice, good customer service they put me on the UKARA database in mins and even gave me a £15 voucher so all in all a great experience.