@too_sleepy
Since this occurred at LHR can I suggest you file a
CHIRP report? It won't be used for disciplinary purposes, but it may stop it happening again; the fact that this crew got away with it once is no guarantee they'll do so again, never mind the fact that what they did is almost certainly a violation of the relevant operational regs.
@sleeper
Its not even in the OEM's control - the rules pertaining to the clean aircraft concept are in the operational regs. There are a couple of grandfathered cases that violate the regs (a very murky area, legally, IMHO) but the regs themselves are pretty clear... 121.629 is the US airline version of the rule, but the wording is pretty similar everywhere. So pretty much everyone is (or should be) in the same boat.