I actually found the firmware you sent the link to after posting my question, It flashed and branded the box as O2 just fine, but it would only allow a fixed static ip address setup. It wouldn't work at home (tried it tonight) so called up O2 and as the previous reply said (thanks!) they offered me a new router FOC, with no more ties or contract extensions. Result, albeit a different one!
I have 2 x TG585V7 routers now, neither will be any use on O2 or Be but never mind! I will see if the new router sorts my issues, I cannot complain about O2 by the way, they have some bad press on here, but they've been brilliant, keeping costs down as I have a legacy package that costs les than £10 a month for unlimited downloads, and my postcode has some very poor speeds (<2MB) but I do get 2.5MB so it's the best of a bad situation, both neighbours have BT at less than 2MB. Infinity is in the area, but not as far as my street - just my luck!