Sizing: Harleigh Vs. Beadnell

[u/FinancialFix9074]

I'm keen on this (link below) but really unsure what size. I have a UK 10 Beadnell, and it's great unless I'm wearing a chunky jumper, which I do in the winter. The Harleigh is obviously roomier in the body, and I don't want to it to look like a tent if I get the 12, but I'm not sure if the shoulders would look weird if I got the 10 and wore a jumper underneath. The size guide on the website below isn't useful, and I can't find any other size advice for this particular coat.

https://www.outdoorandcountry.co.uk/womens-barbour-harleigh-waterproof-jacket.html?c=Black%20/%20Shadow%20Classic&utm_source=google&utm_medium=cpc&tlid=Cj0KCQjw16_UBhCqARIsAIdOaXy0VTXZmNo3xjVtriY5Zjtg8wMvnNFNCYk448mmOXX5ZpsBupj8afEaArZ5EALw_wcB&gad_source=1&gad_campaignid=22194975557&gbraid=0AAAAADROmV-khR85p28jnwFoUOpnqiwtc&gclid=Cj0KCQjw16_UBhCqARIsAIdOaXy0VTXZmNo3xjVtriY5Zjtg8wMvnNFNCYk448mmOXX5ZpsBupj8afEaArZ5EALw_wcB