So I tired this on today in John Lewis. I'm a 30E normally, so I tried the 30E and then when it didn't fit that well, the 30F. I'm totally on side with the idea that backs must be tight, and I think the 30 back was right for me - it definitely would have been a good fit on the loosest hook, and allowing for stretching, good long-term.
But I find it impossible to do up bras with three hooks behind my back, and the sticky silicone bands make it really hard to get these bras into the right place if you do them up in the front and try to swivel them round, especially once you get hot.
If DP was always going to be around to do them up for me, I'd go for the 30 band, but what if he dumps me for someone with smaller boobs I am getting dressed alone?
Is there a secret way of getting these bastards fastened? Or should I go for a 32" back?