I measure a 26 band, but haven't found any! I find M & s 28dd plunge bras with slight padding very comfy. I normally get them off eBay. (I have measured one at full stretch and they run small, maybe they are factory seconds?)
I'll look. When I was younger I could get away with a rubbish bra/ no bra. Then I had some lovely bravissimo ones pre kids, then I dropped a cup size, I think I'd be better off if I put on weight, but easier said than done.
I'm a 28d but it's such a hard size to get there's almost no choice. I had the same problem with underwire being uncomfortable on my ribs, I went to a 30c to see if it would help but had to bin the £22 debenhams one because it was so uncomfy. I have recently bought loads like these from h&m with no underwire and they have been a revelation.