Restoring old glass plate photo?

[waspexile]

Not really sure where to post this but in the family we have an old glass plate photo (we think about 1900 but could be earlier) showing my maternal grandmother as a baby, with her mother.

The blacking is coming off the back of the glass and the image itself is discoloured.

Does anyone have any good ideas of who to contact with a view to any possible restoration? I've done a bit of Googling but with not much result.

[AnnB]

I know nothing on the subject, but I do know of someone who had a similar problem and got some help from a local photographer who had an interest in glass negatives. Are there any photographers local to you who may be able to help?

Best wishes
Ann