IIRC when Iwas looking for one
RD Aviation are the agents for GQ Parachutes. RD are on the south coast somewhere (Bournemouth rings a bell but I'm sure that a web search will yield better results than my mind's campanology!)
Didn't buy a GQ (not because of the Gucci-esque name) but used one a couple of weeks ago and it was fine - I say used what I mean was wore one! I have a mate with one and he gets on well with it.
Ended up buying mine from Paraphernalia in the States - an airline pilot buddy collected it for me (he naturally declared it and I paid the duty & tax). At the time the exchange rate was more favourable and my 'chute came in at less than £700.
Am very happy with my Parphernalia wedge and wear it every time I take my toy up. I really hope that it is never required as anything but a very expensive back cushion!
Stik