Belinda,
Hang fire for the moment on buying a birth cert !
On the 1861 census, in East Ditchburn (page ref 3880-80-3) Mary, william's wife is aged 31 (born Alnwick). On 1851 census (ref 2419-652-1) she was 20.
On 1871 census (5175-74-1) William is recorded as a widower.
The births of Ralph and Matthew were registered with Alnwick Reg District in the June Qtr of 1866.
In the same registration district there are death registrations for several Mary Taylors. The best candidates for your Mary Taylor ...
Sept Qtr ( so registered from 1st July to 30 Sep)1868, aged 37
June Qtr (registered 1st April-30th June ) 1869 aged 38
The best bet is the first one.
~~~~~~~~------
Now that I have tuned into the "twins" situation, I think the couple had at least 3 sets of twins, including William and Margaret, registered March Qtr 1851.
You can see them, and a 3 yr old dtr Mary who died in infancy on 1851 census (ref 2419-652-1)
Ogle Arms. What records do you have that show that the family ever lived in the Ogle Arms ?
Michael