Please help identify this set of my Dad's - DD mark, Derek Day

Hello...  We are sorting through my late father's stuff.  He collected a lot of pottery, much of it from Yorkshire (eg Shelf Pottery) and Cornwall (eg Carn).

We've found this small collection which all bears the same distinctive mark, together with the same brown circular ridges on the base (see photos).  

Would be really interested if any of you experts could identify where it's from.  We've tried a Google lens search on the mark but not had any joy.

Thank you in advance

It does not look like a well known mark .While nicely made, they are fairly basic mugs of which there  are a large number around. If you are settling your father's estate I would say check the value of studio pottery mugs on Ebay.

Welcome to the forum. The mark is for Derek Day. As Philpot says, competent work but not a well known potter

https://www.20thcenturyforum.com/t21192-dd-mark-derek-day

I bow to your vast knowledge Naomi!

Brilliant, thank you both for your help