The ECC32/ECC33/ECC34/ECC35 and probably a few more were all made by Mullard in UK.
I have a some 6SN7 Mullard, branded as made in England which is also wrong.
Mullard never made any 6SN7.
They were made in Holland or Belgium.
I have American 6SN7GTB's marked as 5692 and vice versa.
Some late Mullards were made in CCCP and marked as made in England.
You must pay attention to the construction, plates, getter etc to be sure.