There are loads of energy saving bulb offers but nearly all seem to be for the standard size bayonet or screw caps. Found these small screw bulbs at Tesco. £1 each or buy five for £1.
9 watt / 40 watt equivalent - last ten years.
They have now removed this offer on all but the 11w BC lamps
Tesco Orpington still had the offer label on the shelf for the 9w BC lamps, but on getting to the till, the offer was not there (they did let me have them for the price advertised, but I didn't get an apology for the inconvenience - miserable cow manager!