I am not sure which parish records you want searched.
The 1851 census shows James aged 40 together with children aged 17, 15 and 4 - which suggests that Martha was alive to give birth 4 years before. The only death for a Martha Poor/e in FreeBMD was in 1850 for the Alton district - which could be her. Sadly my fiche of Newton Valence burials are unreadable for that date so I can not get an age at death. You will need to go to the Record Office for this - if it is not clear there - they should let you see the original register.
That will give you an idea of when she was born - with a father named William - although we do know that she was 21+ at the marriage in 1841. If you can find the age at death - we could look for relevant baptisms? Yours Jane
