Dear Sue,
May I take you up on your kind offer to check the following queries at the Hertford CRO

The birth / baptism of Richard BLAND, possibly in Thrapston from the marriage you gave me
The birth / baptism of Sarah ENGLISH, she married in Hitchin 21/9/1721
The deaths / burials of both Richard & Sarah – the last child was baptized in Hitchin 8/12/1738
From the IGI, the baptisms of their children in Hitchin
Edward BLAND 24/3/1723/4
Sarah BLAND 20/7/1726
Edward BLAND 18/5/1729
Mary BLAND 24/3/1732/3
Ann BLAND 21/1/1734/5
Henry BLAND 14/9/1737
James BLAND 8/12/1738

From the IGI 1/5/1757 the marriage of Walter RENCH & Mary BLAND in Braughing

If you can find any marriages or deaths for the BLAND children that would be great

Best wishes,
Mikle Horton