Years ago (late seventies/early eighties) we made an approach to Cologne behind a Lufthansa in marginal conditions. He landed, we didn't, so went round for another go. He reported cloud base figure well above our DH and we still saw nothing so diverted to Dusseldorf. It wasn't until we were safely on the ground that we realised his cloudbase report was based on QNH, whereas we at that time used QFE.