My resistance collapsed when a stowaway in rideable condition cropped up on the Glasgow FGSS forum for a mere £25, so I'm now the (slightly guilty feeling) owner of a 1980 Raleigh Twenty. Had great fun riding it back to the flat - it manages to be nippy yet relaxed at the same time. It's got a SA 3 speed, which I'm already itching to take apart to try and sort a slight squeak. Racks front and back, British racing green (ish), and enormous lights. Sadly no bottle dynamo, so I'll keep an eye on ebay for something going cheap.
Could also do with some fresh tyres (451 size), so if anyone knows of any old ones lying around not being used, do let me know...