I'd also really recommend an American guy called Vic who is based in a company called Midland Mars in Bloxwich, near Walsall.  He's good value and uses only top quality film - sure he could also source something particular if you required.  
I've only had my car about two months but am a bit particular and the poort quality tint on the rear screen of my E30 was bugging me everytime I looked in the rearview mirror.  He removed the old tint film from my rear screen and re-tinted it last Saturday and it's perfect.  Midland Mars has a website which is pretty basic but could be worth look and a chat on the phone to Vic.  I also have his mobile if you're interested.