Real numbers of Uk traders

Hello guys, i am in what appears to be an anxiety provoking quest of finding out how many traders are out there in UK. I realize that some are doing FX, some CFD, some are regular, and this complicates the research even more. I have read countless company annual reports where they talk in general terms of international active accounts but never about the specific UK market. What i am truly after is the projected nr of traders that could use Level 2 data, the order book. If everything goes fine, there will be something coming out that will change from that moment the game, the rules, the dynamic of it all, using technology for the benefit of us, the traders. Any help with directions, numbers or contacts will be very much appreciated. Best regards