(30DD/28E is a sister sizing match - if you go up a band size, you go down a cup size, if you go down a band size, you go up a cup size).
I still find this hard to get my head round.
In my mind - a bra measurement, the number corresponds to the band size - the cup size being the difference between that and across the bust measurement. I guess this is right, but when you need to go up a bit or down a bit you try a sister size.
So, we don't have 38 band on our list.
I have my doubts about the stats on Maria Whittaker are accurate, 38 band seems too big - https://www.boobpedia.com/boobs/Maria_Whittaker - 38E?
Remember three key things about bra fitting: the bands are only available in even-numbered sizes (28, 32, 38 and so on), but the bands have rows of hooks and eyes to compensate for variances in back sizes. Also, the bands have Lycra in them (most do, anyway), so that helps compensate. And, finally, when you move up or down a band/cup size either the band or the cup changes to compensate for the variance in size (eg. a smaller band with a bigger cup size, or a bigger band with a smaller cup).
As for Maria, here’s what I wrote before about her here on the BEA:
A beautiful woman, and along with Samantha Fox, another example of what was considered “big boobed” in the late 80s in the UK, but wouldn’t be now.
She would probably be a 32G or a 30GG now. It’s hard to tell her frame size, but I remember she did a nightclub tour of the UK in the 80s and visited a club where I lived in England at the time. All the boys were very excited to meet her. She signed photos and took pics with them, giving them a peck on the cheek. She was so glamorous and pretty up-close. And she seemed so tall as well - but she was wearing 4” white heels!
I’d say 30GG.