I'm in M&S now trying on bras...

[MI5agent]

...I'm a 30 around my back, they've added 4in so saying I'm a 34, and a C cup.

I think I'm more of a 32 and higher cup to tuck all the boob in (I'm not big but saggy so need to lift them!)

Is this how they size? Do I let her do what she says and try on other sizes!

Arrrh I just need a bra that fits!

If you are quite ribby then I would start with a 34GG/H and even an HH and work from there. First thing to do is try the bra back to front - that lets you test the band size without the cups getting in the way. Once you know which band size is best then you work through the cups. If the band feels ok back to front but too tight the right way round then it actually means the cups are too small and stealing the band fabric!

Good to know, thank you. I will do some trying on!