I haven't been measured for about 6 years, but nothing has changed in all that time.
I loved the M & S bra sets when I was living in London. But I am just a 34A. Hell, I could probably fit into their 'Angel' range. I would simply grab heaps around the right sizes in all different styles and try everything on. Then I would buy all the colours that the best one came in.
My housemate hated M & S with a passion, but she was a 40FF. Bravissimo was her favourite place for bras. They don't measure you there. Everything is a 'try on & see if it is comfy'. They have some really good sexy sets and everyday stuff. It is a bit pricey, but their stuff lasts if you use a bra bag when washing.
I think I have the bra from Ann Summers that you were talking about
. Their stuff is pretty good.