You have it John Walker. It is indeed the church with a double dedication of St Mary and St Eanswythe, the later you rightly said was a seventh-century member of the Kentish Royal family. Originally founding a minster at Folkestone, the chapel where her remains rested was inundated by the sea eroding the cliff above which it stood. her remains were transferred to an adjoining priory, which was subsequently moved, with her remains, in the twelfth-century to a new location, which is where the present church stands. Her remain appear to have been concealed in a niche in the north wall of the chancel possibly during the early years of the dissolution only to be discovered during the mid nineteenth-century restoration of the current church. Its these remain hat have recently been re-examined with carbon dating showing the skeletal remains are those of a young woman who died during the mid seventh-century.
You are right in the fact that the church is much larger than in the drawing, which is due to the nave having been largely destroyed during the eighteenth-century and replaced with a brick 'barn-like' structure. this can be seen in the sketch, and was replaced with the present nave in the mid nineteenth-century.
Over to you John Walker
