Going to LHR this weekend but doing BA instead of CX because I'm in J and not F. Have to transfer T5-T1 so I'm carrying all my luggage on. I carry on a massive wheeled-garment bag which looks way too big to be carried on board, but it does fit in the overheads. I bring it on all the time on CX/KA flights and as DM no-one ever says anything (because I get the orange tags), and it always fits in the bins anyway. But it clearly is way too big per the dimensions allowed.

Anyone know if a.) the BA ladies will give me one of those orange tags to get past the anal luggage-checking ladies? b.) if they won't, can I walk over to the CX stand and, even though I'm not on CX metal, ask them for tags?