No M very few are marked but a friend has or had a marked one the same as Ivos and mine , i believe it was Liberty that insisted theirs were marked as was often the case in those days , also about the bubbles , its like saying its not Whitefriars because its not got bubbles but it was only a certain period that most pieces from Whitefriars were bubbled , if you check the books on Clutha the pictures show many pieces without bubbles , in the early books most pieces were bubbled because they didnt recognise the pieces without bubbles as Clutha , one of the best books on Dresser and Clutha is a fairly new book by a friend of mine Chris Morely , Chris is an associate of Harry Lyons , if you know Dresser say no more .