If they are working in France then, as you say, the CEAM is appropriate. If not, then without an S1 it’s the GHIC, issued by the UK.
I thought @KarenLot had summarised the situation correctly and succinctly.
1 Like
Was surprised to receive my replacement EHIC last week as the present one doesn’t expire till November and I hadn’t yet felt the need to request a replacement (an observation, not a complaint).