I found a Grifter in the local brook that was obviously nicked and dumped. I took it home and hosed it down, and my dad did the honourable thing of reporting it to the police. After 14 days he got a call back from the police to say it hadn't been reported stolen, so I got to keep it.
I ended up completely stripping it down, cleaning it and fixing it back up again. Even the 3-speed Sturmey-Archer hub gears. Took a while and a bit of research (old school library books on bike maintenance), but it was well worth it.
I remember that thing being the weight of a small neutron star, but it was a great bike. Sadly long gone.