Took a detour to Bourne Abbey on the way home the other week just to get a south aspect picture for my Pinchbeck fen map project.
Of course the E arm is gone, and the site of the crossing replaced by a post-Dissolution banged-together chancel.
The Pinchbeck Fen map of c.1430, probably made at Spalding Priory, is such a thing in itself to discuss (and the post is probably long enough as it is).
This is what I've managed to decipher from the images I can get of it (frustratingly there is not one big high-res one available!)