Rosie99, as far as I can see:
Jane 24/28 Nov 1791, Cornhill, Northumberland
Marey 4/8 Feb 1798, Cornhill, Northumberland
There is also Calender (female) 8/12 April 1803, Cornhill, Northumberland.
It is the distance of Cornhill-on-Tweed to Houghton-le-Spring (which is where Alexander and his wife and children lived) that bothered me - 72 miles. Having said that, Alexander's first child, Euphemia Robson, is recorded on the 1851 census as being born in Scotland. Just finding the different Cornhills of Durham and Northumberland a bit confusing.