There has been a long-term problem between Tesco and its clubcard deals providers which has shown itself many times.

When a company joins Deals, they expect the average converter to be changing £20 or so per quarter. They never, in a million years, expect a few hundred people to come out of the woodwork with £1,000s-worth. That is why Motorpoint pulled out sharpish, as did a lot of the holiday companies - because they were losing huge amounts of money on Tesco Deals transactions.

This is not necessarily the same as the BA/Tesco double up situation, but BA probably did give away far more miles than expected. (That said, it also generated some very handy cash.) Some of those who converted to Air Miles are probably regretting it, even at double up, given the recent devaluation.