Hi Maxie,
I got this from Freecen, I take it this is your family:-
1851 Census
8 Records found
Piece: SCT1851/717 Place: Prestonkirk -East Lothian Enumeration District: 4
Civil Parish: Prestonkirk Ecclesiastical Parish, Village or Island: Prestonkirk
Folio: 0 Page: 2 Schedule: 5
Address: Phantassie
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Surname First name(s) Rel Status Sex Age Occupation Where Born Remarks
DARLING Christopher Head M M 33 Coachman Berwickshire - Dunse
DARLING Catherine Wife M F 29 Perth - Errol
DARLING David Son U M 8 Scholar Midlothian - Crammond
DARLING John Son U M 6 Scholar Stirlingshire - Falkirk
DARLING Margaret Dau U F 4 Stirlingshire - Falkirk
DARLING Anne Dau U F 1 East Lothian - Stenton
DARLING James Son U M 1m East Lothian - Prestonkirk
EDMOND Anne Mother W F 48 East Lothian - Dirleton
As Ann has a W for her marital status it would appear that David died pre 1851.
Freereg has some very good East Lothian records. On there I found this one, I'm not saying he's yours but it's one to bear in mind, given where the family are in 1851:-
County East Lothian
Place Innerwick
Church Innerwick Parish Church Vol V
RegisterNumber 48
BurialDate 02 May 1848
Forename David
Surname DARLING
Age
Abode Westhall
Notes
If he's yours then he should, in theory, appear on the 1841 census somewhere.
Does your 1841 census have a maritial status for Anne?
Best wishes
Donna
p.s. On Genes Reunited there are a few people with Christopher Darling of Duns born circa 1822 listed. Those people also have David Darling of Duns born circa 1779 - 1800 listed.