Genealogy Forum UK

Hi all,
I have a DNA match via Ancestry.com with whom I share 335cM (5%) across 16 segments. This is a significant percentage but the individual is not known to me. I've attached a screenshot of the possible relationships and the percentage likelihoods.
My strong suspicion is that this is a half relationship coming directly from either my paternal grandmother or her parents (I know that it's this line based on other DNA matches). There might also be one generation difference between the match and myself.
Given the information above, can anyone help with narrowing it down please i.e. grandparent or great grandparent?
Happy to answer questions and thanks.

this may help

https://dnapainter.com/tools/sharedcmv4

does it say paternal or maternal on the Ancestry chart have you any other none sibling that have been tested beside you what is their given relationship to them if so?

any off the shared matches between you and this match close? what the cms difference to them?

do they have a tree you can view?

Thanks for the reply. The match doesn't have much of a tree but I've established (via one of their cousins) that their mother was adopted. Given the date of this, the only conclusion I can draw is that my paternal grandmother was the biological mother of the match's mother. The only doubt I have about this is that my grandmother would have been in her early 40s, married with an 11 year old son (my dad).....who if he knows something, isn't saying. I can't see any other explanation though.

how old are you was the baby born during the war as quite a few kids were put up for adoption because women got pregnant whilst husbands serving away i have a couple in my tree

you can also look for a child born in the area your grandmother was living at the time it may have been registered before adoption it might have your grand mother married name and her surname before married on the register

The match's mum was born in April 1945. The adoptive family were from Coventry and my grandmother was living in Birmingham. However, my limited knowledge suggests that my grandfather was working in the Lonbridge factory as an engineer on Hawker Hurricanes....so not abroad. I've looked for babies born with either married or maiden surname but there's nothing obvious.

you sure it not your grandad the father? or did your grandmother have any siblings? that it could be?