Good heavens - what quick replies!
Yes, her parents were William Gunn and Phoebe Millington and that's them on the 1871 census groom.

I think you are right about the 'Tongue' part of her name fifer1947, if not it's definately a possibility.

rosie99 This is her isn't it and I did wonder if her birth was never registered. One of the reasons for sending for the her marriage certificate was to see if her father was William Gunn. William and Phoebe (married 4 August 1846) had a son William Gunn Millington born abt 1846 a daughter Mary Ann born abt 1848 and then Isabella born abt 1867ish. I haven't found any other children. The gap does seem very large between them and I too wondered if maybe Mary Ann was Isabellas mother as she is the right age. As the father is listed on the wedding cert as William Gunn, maybe they lied to cover a 'base born' child or is there something else going on?

Thank you for your help, it's greatly appreciated.
Linda