Thanks for the clarifications guys .. Out of interest on UK-Germany Lufthansa fares don't have similar conditions ... their more expensive economy fares (xFLEX11) all say:

CHANGES ANY TIME CHANGES PERMITTED FOR REISSUE/REVALIDATION.

And the cheaper Lufthansa Economy fares (xKOMBI11) all seem to be upgradeable for a fee without any obvious day of departure restrictions (In fact in the rather long winded rules it seems the £35/€50 fee might be waived if you're upgrading to a FLEX fare)

By way of comparison SWISS for Zurich flights seem to be more restrictive than than LH but still allow more flexibility than BA ... They only have the non changeable on day of departure condition on HWSISSUK and below (which is SWISS terms is sub £250+tax round trip fares)