Thanks JM.
I got hold of the marriage certificate for William Webster and Ann Leslie, she was indeed born Ann Glasgow. The unfortunate Mr Leslie died the year before the marriage, he and Ann had no children.
William Webster was born in Galgate, Lancashire, his parents were Thomas Webster and Agnes Watson, hence the name of one of William and Ann's daughters.
Now if I could only find what became of William.
Edit:
Ann's age on her marriage certificate is given as 27, which would make her year of birth 1839, is there something amiss in the Scottish records from earlier in this thread?
If she was in fact born in 1828 she would have been 38 on her marriage to William Webster and 43 when her youngest child was born, something doesn't add up.