As could be seen from the "Water of life" shots, I was not quite managing to get hold of this "glass" genre. When all else fails, listen to good advice, and read the manual.
Sherry glass mono
Sherry
EDIT: I realise that the glass in the B&W shot needs to be centred but got carried away a bit by actually getting a half-decent "Glass" shot.
A big thank you to Mike B!