Thanks larryflyer - have updated the list. Which airlines have you used? Would assume all the majors are covered, but I wouldn't be surprised if a few slipped through the net.
Anyone else get triple MRs at Tesco petrol stations, or is this a freak result?
P.S. I foolishly did myself out of 10 BMI miles by testing the water with an Oyster topup yesterday. So I think it's well worth pooling our experiences.