Thanks for the warm welcome. Plenty to think about. Any more suggestions... feel free to keep them coming! If size wasn't such an issue I'd be sneaking my Mum's Kef Concertos out of her house! Mind you, I'm not sure if they're rated particularly highly by those in the know
You beat me to it. The old KEF catalogue is exactly where I would be looking.
They made some excellent speakers, at a time when you didn't need significant amplifier power.
As far as I know the old KEF don't have major age-related issues, other than tired crossovers needing rebuilding.
I would rather listen to a classic pair of KEF than many modern speakers.
There are so many old KEF about that their prices are very modest.
Ideally you need to be looking at speakers with a 90db efficiency rating or higher. At shows I have to say I have not heard what i would consider a bad speaker from the firm Triangle ..Triangle Borea BR03 comes in at just over your £300 budget. Also as others have mentioned there are great bookshelfs from Q Acoustics and Klipsch.
Others that may fit the bill (check the second hand speakers on ebay) are the Dali Oberon, Quad S1, and others such as the Celestion Ditton 10 and 11 (great small speakers), Castle mad some great small speakers as well.