Frederick Tatham (1805-78)
From Anecdotes about Eighteen Century Authors

Became the friend of Blake and his wife in their old age. On Blake's death, Mrs. Blake stayed for some time with Tatham and his wife, and was apparently very fond of them. Tatham's account of Blake's last hours must be based on what Mrs. Blake told him, and although there are signs of dramatization in his narrative, the facts are probably authentic.

Note from William Blake, from Literary Anecdotes