No probs Newbie,
Here we are - looks like William must have died though......
Ref HO107/1177/10 Folio 7 Page 7 West Common, Horningsham
Sarah Marsh - 40 - Independent
Frederic Marsh - 20 - Chairmaker
Both born in county
In 1851 we have -
Ref HO107/1843 Folio 399 Page 19 -West Common, Chapel Street, Horningsham
Frederic Marsh - Head - Mar - 31 - Turner (pill boxes) - Wilts, Horningsham
Ann Marsh - Wife - Mar - 26 - - Wilts, Horningsham
Edward Marsh - Son - - 5 - Scholar - Wilts, Horningsham
The only possibility for mum Sarah I can find is this, rather puzzling one.....
Ref HO107/1843 Folio 386 Page 40 -West Common, Horningsham
Sarah Marsh - Head - Mar - 54 - Husband a gardener - Wilts, Horningsham
Elizabeth Marsh - Dau - U - 26 - Servant out of place - Wilts, Horningsham
So - not a widow? Where has the husband been for the past 10 years? Certainly not in Horningsham, at least as far as the indexes show...
The other mildly interesting thing is that Sarah is living next door to Lambert Trollop in 1851
Do say if you want any other bits of this checking

Best wishes
Angela