You may remeber me starting this thread a while ago, I've sovled the problem now though. It was dodgy HT leads. Fitted new ones this morning and it doesn't pink now. Suprisingly I haven't been able to notice an improvement in performance (apart from when the engine was pinking). I'm going to see what my fuel consumption is now and hopefully see a sudden improvement.
[Car - V reg Fiat Seicento SX 899cc]