They will almost certainly be UK 9.5E
Hopefully they have the original box and it will provide clarity. I’m a 10uk typically and 11 US.
...and therein lies the conundrum. A while back I read back through multiple similar exchanges on this thread regarding these RL Marlow's and the sizing conversion. I settled in my mind that it is a full size down US to UK, although the box that these are coming with says US 10D and UK 9.5E.
If they are indeed a UK 9.5E equivalent to the Pembroke they will be too big for me. I can just about squeeze in to a UK 8.5E, but prefer a bit more space of the 9.