quartermilltopo, although yours was a pre-JAR-FCL 'AFI' Rating, the renewal requirements are probably the same as for a JAR-FCL FI(A) Rating lapsed by more than 5 years:
1. Attend a FI refresher seminar approved by the Authority within the 12 months preceding the date of application for renewal,
2. Pass a FI (A) proficiency check within the 12 months preceding the date of application for renewal (you will probably need some refresher flying first!),
3. Submit completed form SRG\1153 to demonstrate to the satisfaction of the Authority that knowledge of the relevant parts of JAR-FCL and JAR-OPS has been acquired.
4. Send the renewal application to PLD for endorsement together with the appropriate fee as per Scheme of Charges.
That's as I read it, but you should check with a FTO authorised to conduct FI training.
You will probably also need to renew your SEP Class Rating.