"I have an Enfield Marriage, St Andrew from Ancestry.co.uk 1880. The registration district is Edmonton." Yes that's quite correct, Edmonton is also in Middlesex, or at least was until being absorbed into The London Borough of Enfield. You must remember that Registration Districts do not follow County boundary lines. For example Waltham Abbey ( Waltham Holy Cross ) is in Essex, always has been but is in the Edmonton Registration District or was but the boundaries seem to change like the weather. Regards, Mick