Tungsten Halogen Bulb 150W 240V 78mm
As used in the smaller PIR etc floodlights and some uplighters.
Edit: Thanks to Gold1e - these are apparently online only so don't bother unless your total order is >£50 (otherwise £5 P&P) - and remember approx. 5% Quidco
Edit2: Thanks again to Gold1e - see posting below for link to 1000W