Send a message to the person who requested a photo of the grave monument of Mary Ann Lidstone with the following comment:
Hi - my forebears were George and Elizabeth Ryder of Aveton Gifford and their son George, also of Aveton Gifford who was born in 1806/7. George (the son) either married or had a defacto relationship (and 4 children) with Mary Ann Lidstone. The age of this Mary Ann lines up - she would have been 27 in 1841, when the first Census data was captured. I am hoping that the image of the monument may give me more information. I live in New Zealand, so can't provide physical help with your work, sorry.