Plate 1a - lettered AA from Spalding to Folkingham. 2 strikes of the Spalding Maltese Cross and 2 strikes of the "Spalding" undated circular town stamps with Paid stamp of 15 June 1840 and a handstruck 1d.
Presumably routed through London, so adding 200 miles to the journey, even though they are under 20 miles apart. The Spalding postmaster on the A16 route misread the destination, hence the word 'Lincolnshire' being added to the address, in London, to get to Folkingham on the A15 route.