Thank you, David.
I will follow up on the points you make.
I think John and Martha baptised their children in Sandy. I can see a couple of deaths registered there aswell as the births (1739 - 1758).
Re the marriage, there is nothing else on the LDS or FreeREG so I would need to follow up on the microfiche and hope it contains other info. Martha was baptised in Blunham so there must be a 'Sandy' connection with them marrying there.
William's abode is given as just down the road in Hitchin, Herts on the FreeREG burial entry. Perhaps he lived/worked there but came 'home' to Sandy to be buried, perhaps not. I take your point re he, William, being the first 'Lincoln' to be entered in the Sandy PR's so I will continue to try and locate himself and siblings elsewhere.
The BLARS info would need a photocopy ordering so I could look into that.
I accept possibilities 2 and 3 should be ignored. I thought to include them on my original posting as it may have helped.
I trust that it is not as 'white' with yourself as it is up here.
Kind Regards,
Mark.