I purchased an Evopower silenced diesel generator last year from Genpower down here in West Wales (always good to buy from companies just down the road - if it turns out rubbish you can drop it back on their doorstep!).
Current link is
http://www.genpoweruk.co.uk/Evopower_LDG6000S_Silenced_Diesel_Standby_Generator_5kw.htmlPrice has gone up a bit (we had the benefit of a special deal) but it fitted all my criteria - key start (you need to charge the starter battery a couple of times a year), what appears to be a well smoothed output (although I would still run the computers through my surge protected UPS to insulate then from fluctuations in voltage and frequency). It is rated to 5kw which means it will run everything - keep the freezers going whilst running the oven, lights and the telly if needed! Best of all it runs on red diesel!
It is heavy (about 170kg) but on wheels so not too much problem and is remarkably well silenced - the casing and insulation does a pretty reasonable job. Wouldn't work on a market stall perhaps, but outside the house you wouldn't hear it from inside. Our neighbours are well away so no issues there.
I had originally intended to put solar panels in, thinking that would work reasonably well as a daytime backup. Not a chance! What they don't tell you is that when the mains grid goes down, your panels are disconnected (they need the 50Hz from the grid to synchronise and they don't want you killing the repairman up a pole in the next village.
Having said that, we haven't had a significant power cut in the time since we bought it - despite very heavy snow in January - but it is nice to have it around!