LOL - it's OK when it's Tesco though!

To be honest I thought of doing the same when I've had too much time on my hands at T5 but I came to the conclusion that I had above, that it might result in a wasted trip for me if they do check the gate for the flight, or if BA checks these things might give them an excuse to pull the benefit (I'm not saying they would if one or two would do it, but good ideas go viral here and we could see many people also doing the same if it works).

I'm not someone who's going to criticise you if you do give it a go. Different people find value in different things. Just if you give it a go make sure the walkway is not closed off for any reason, so I'd suggest walking to C gates so you know it's OK.