Marigolds work: Carrier Bags don't.
Until I can afford to spend £30 on a pair of socks(!) I thought I'd try a carrier bag on my foot inbetween two layers of socks. This didn't really work, although probably did delay things for a bit. Unfortunately I can no longer use my home made waterproof overshoes with my road bike as they catch on the chain ring and front derailleur.
Using marigolds inbetween two layers of gloves works very well though. Fetching pink colour as well.