.303 ?
St. Nazaire was something of a go-to spot for soldiers able to take a break from the front. Known for, among other things, its brothels apparently!
Sorry I didn’t get a shot of the head stamps. The brass have some cut out coin seals on them. The obvious .30-06 has an eagle/shield. That 30-ish rimmed cartridge was decorated with a crown of sorts. Felt Britishy, but could have been French.
The head stamps definitely were gummed up and a bit corroded, but no obvious numbers. More like proof marks. The rimmed brass had something that looked like a triangle and then a couple of slashed lines. I’d probably recognize them if I saw another similar image of them. Will do some googling.