It makes total sense - for a start, the 'fee' of £140 is partially offset by 6,000 bonus miles on a 24k transfer, plus another 1,700 miles if you're on the Lloyds Amex 12.5x promo.

Obviously you can share for free with a HHA. But if want to issue tickets for friends outside your HHA, then you are stuffed if you open one. This lets you move miles in at a relatively cost effective basis.