Thanks for your replies, guys. The problem is that I can't compare like for like between the LH and Opodo websites. LH says "ZRCGB" but Opodo says just "Z" for a fare that is identical in price (give or take a few pence). But I gathered that the LH website fare rule information is useless as it errs on the side of caution and often says "fare is non-refundable" even though it is, right?