I am fanatical about a decent bra and am a long term critic of M&S and their terrible fitting etc. But...I bought [[https://www.marksandspencer.com/cotton-rich-full-cup-t-shirt-bra-a-g/p/p60164305?image=SD_02_T33_3083_UT_X_EC_90&color=GREYMARL&prevPage=plp&pdpredirect
this]] bra on a whim with a view to wearing it under my pyjamas. And to my amazement it is actually a good enough fit and shape that I could wear it in public without looking like a sack of potatoes.
I normally wear a 32H and bought this in a 34G and it's fine. It's not as supportive as a wired bra, but it's a lot better than I expected it to be.
I thought I'd share as it may be of interest.