No more brokers' circulars! Five of the UK's largest stockbroking firms have decided to do their bit for saving the rainforests by delivering research electronically, straight to the desk tops of fund managers. The brokers, which include SBC Warburg and NatWest Securities, reckon that last year alone they published more than 18,000 pieces of research which used over 1,600 tons of paper pulp - representing 19,500 trees. They also employed more than 2.3 million individual courier runs to deliver the stuff, generating untold amounts of Kawasaki 250 exhaust fumes. First Call Research Direct is the outfit delivering the material screen-to-screen. It may be a green idea, but it's a …