Ian_m coughed up some electrons that declared:

You can get a capacitor that you wire in parallel with the low energy bulb
which allows enough electricity through to power up the dusk to dawn
switch.

http://www.tlc-direct.co.uk/Products/SMFLA01.html
Bit bloomin steep if this is a capacitor, I am sure I only paid £2 for
mine, pushed in into ceiling cavirty behind ceiling rose.

Downside is the low energy bulbs flicker faintly when off and from what I
have read some types of low energy bulbs glow permenantly and have
seriously shortened lifetimes.


Megaman have dimmable CFLs, designed to work with regular dimmers.

Might be worth looking at?