Geof, pretty much anything has a nice big sensor compared to a compact, and you don't have to go to full frame to get extremely high quality these days (even if that is remotely within budget).
These things always boil down to budget and at the entry level end Nikon D40 and Sony A200 will do the business. Or something similar - not sure what the latest models are, but there are no truly bad cameras about these days. However, the outfit that does it best IMHO is the Canon 450D with 18-55 IS (£470) and then 55-250 IS lens (£160) for a bit more reach.
It's got plenty of pixels on a good sensor, a nice screen, the basic kit lens is very good and the little 55-250 is a gem for really very little money. Then stick a 430EX flash on it and you're really rockin. Get a Raynox close-up lens for £40 for some macro fun. And with the future in mind, it's part of the biggest camera system known to man with the full panoply (spendid word, I must use it more often) of Canon kit just a pin number away.
You'll find the best prices on CameraPriceBuster here
http://www.camerapricebuster.com/index.html
It's quite a small camera - might even fit in your anorak pocket