At last, I have been able to speak to the real experts! and they tell me that they have now explained the discrepancy on Page 107 of Annette Kley-Blekxtoon's 'Leerdam Glass (1878-2003)
The glass at the extreme left is from another service in an adjoining 'box' and is now attributed with some certainty to Gebr. Muller.
This should be noted as an erratum!