Studio Mug, 2 Seal Marks

Can't remember if I've already posted this (apologies if so).

Studio mug with two seals under the handle. The upper looks like the Greek Phi symbol with a longer stick and the lower looks like HF. Any suggestions appreciated.

The HP is probably Haverfordwest pottery. Anne and Theodore Whalley who producee tableware ans stoneware 1962-69. The pieces I have seen have always been of a very good quality. The other mark I don't know, probably another potter who worked there.

But it might be HF
Haverfordwest‘s HP mark. And Paul Whalley usually signs his pieces
https://pin.it/60Tf9v3

I'd have to agree with Naomi, there's no loop for the P so would put money on it being an F. I'd tend towards the upper mark being for the pottery and the lower for the potter.