First tried this in an 80J based on their size chart and some wild ass guesswork based on reviews here of similar styles. That one was too large by one size in every direction but good enough that I repurchased this one. I'm glad I did; it's a great fit and more forgiving of the almost cup-size difference in my breasts' size than I would've expected. It's comfortable and looks good, too. I wouldn't recommend it for someone who was very full on top or wide-rooted but I think it would fit most of the rest of the range of shapes.
The model is BC-560 "Shocked II" and it's simply gorgeous. A bit smaller/less deep in the cup than the same size Kinga Joanna but the band and overall fit are gloriously consistent. Quality construction and materials. The floral and houndstooth play well together and are smooth enough to wear under thinner (darker, of course) tops. I think the 75J would be perfect, being a size smaller in both the band and cup. I'm roughly a UK 34H+.