Jubilee Mug, Madrigal Pottery (not John Maltby)

Can this be John Maltby?...not the kind of thing I've seen of his.
I can hardly find anything about Madrigal and John Maltby together.
Can anyone help?  I've only seen a piece on an auction site but has no information.

Seems the M stands for Madrigal. If you google 'Madrigal Stoneware Lidded TEA Caddy JAR Made IN England' you'll find another one. Seems to be a small company making production pottery in the 70s, but there's little information about it. Maybe Company's House will have some info about the business.

How odd, why would they add a studio-type sprig seal (seems to be in a different clay?),
when the piece is already clearly marked?

Thanks Naomi, yes I've just found other examples with the same M stamp, it was on my mind it was for Madrigal but I agree with DD it seems odd to have a seal when the stamp is quite clear on the base. Especially when it looks, to me, so much like John Maltby's mark, it's bound to confuse some (me)....just intrigued to find out.