William Fletcher's grave specifically mentions "Vengeance is mine...".

 St Guthlac, Little Cowarne, Herefordshire
(Click on an image for a larger version)

Saint Guthlac of Crowland (Old English: Guðlac) (673–714) was a Christian saint from Lincolnshire in England. He is particularly venerated in the Fens of eastern England. Why a village church so far from the Fens should be dedicated to this saint is unknown.
 There must be a "back story" here. William Fletcher was killed rather than died and his grave specifically mentions "Vengeance is mine ...". 
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