M and S bra fitting has been done to death but there seems to be a new development...
www.marksandspencer.com/s/lingerie/be-inspired/bra-fitting-tool?intid=LG_topnav_brasizecalc_txt
Well that's not so helpful
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34C according to this. (Rigby and Peller in shop measure of 30D). I wish there was some vague standardisation in the bra world.