Are the big signs still there at LHR as they seem to have been removed from LGW recently. Plus with the check-in agents at LGW it has changed from being "yes, no problem at all" to check in a compliant piece of hand baggage to, "well on this occasion only I will allow it because the flight is not full" which I interpret as BA no longer will allow it across the board at Gatters

At the non-BA staffed outstations of course it remains very hit-and-miss as it always has been