Unknown studio pottery vase. Any ideas please?

Hi all, I'm after some guidance on this piece please.
It measures 6 inches tall. A few years ago I saw a very similar example in a private collection cabinet of a prominent Cotswold dealer who told me his was by a significant potter. However I can't remember who he said it was potted by and not sure if his info was correct in the first place. Any ideas would be very welcome. Cheers

Is there a mark?
Can you also take a photo of the inside. There are a couple of potters who have a spiral shaft while others are straight (no pun intended)

Hi Naomi, no marks or even a hint of one. Pic is the best i could get. :)