Thanks for all the postings to my query.
The information that I have for my 3x gr grandfather is :
"From the BTs for Chester le Street.
Benjamin Messenger born 23 May 1805 Lumley Park, Co Durham. 2nd son of William Messenger of Lumley Park, Whipperin, native of Swalcliffe, Oxfordshire, by his wife Mary Magin, native of Hawkshaw, Yorkshire"
From Family Search :
"William Messenger = Mary married 18th December 1803 at Kilham, York."
In the BTs for Chester le Street for their daughter and son the name is spelt as 'Maychin' and 'Magin' and rightly or wrongly I have interpreted this as 'Machin'.
The mention of Benjamin being the 2nd son now leads me to the idea that the William Messenger b 12 May 1798 and identified by Suzard is probably the correct one
I have to admit that the thought that I may have skipped a generation had not occurred to me and I obviously need to do some more work on that one.
Wearsider.