Hi Dark Blue - dont know if you have seen it as yet but the Sherington Historical Society
http://www.mkheritage.co.uk/shhs/intro.htmhave an incredible amount of detail on their website. The Griggs were well documented as tenant farmers (both Benjamin and George) in the late 18th & early 19th century. They are shown in the Posse Comitatas of 1798 and the 1796 enclosure maps show the land they were farming as tenants. There are also details of Parish Records searchable by name which may help to identify further avenues of investigation!! Unfortunately the marriage records only go up to 1812 and there is no record of George marrying before that - however it does show the marriage of Benjamin to Ann Rogers in 1774 and also the marriages of
Thomas Griggs to Elisabeth Brown 13 Sep. 1808
Martin Browne baker Jane Griggs 17 Jan. 1810 licence
Stephen Pettit butcher Elizabeth Griggs 19 Jan. 1797 licence
It also has the following burials for Griggs:
NAME - BORN - DATE - AGE
Griggs Ann - Sherington 1824 04 27 - 70
Griggs Benjamin - Sherington 1828 01 24 - 78
Griggs Elizabeth - Sherington 1840 11 25 - 79
Griggs James - Sherington 1832 05 11 - 33
Griggs Louisa Jane - Sherington 1840 09 05 - 6m
Griggs Sarah - Sherington 1836 11 04 - 79
Griggs Sarah - Sherington 1841 05 13 - 24
Griggs Susanna - Sherington 1822 01 17 - 25
Griggs William - Sherington 1822 04 07 - 13
Griggs William Benjamin - Sherington 1842 11 20 - 7
The site has a wealth of info about Sherington so should be worth a look around as the Griggs seem to have been a well established family at that time.
Good luck
DB10