I have just picked up a copy of 'Round Carlisle Cross' by James Walter Brown, (this edition was published in 1951, 21 years after the author's death).

There is a chapter devoted to William Metcalfe which includes the following passage:

[quote]
it was through his association with the hunting song, "John Peel", that Metcalfe's name will be longest remembered, and it now remains to relate how that arose. About this I claim to speak with authority, for I was on terms of intimate friendship with those concerned in the matter, and often discussed it with them.

Up till 1868 the song, as I have said, was sung to the notes of the present refrain. In June of that year my old friend John Clarkson, who was one of that group of clever amateur entertainers whom I have already mentioned, was, on the point of his leaving Carlisle, entertained to a farewell dinner. On that occasion the late Mr.William Lattimer, younger brother of the better known Robert Lattimer, sang John Woodcock Grave's song ,"D'ye ken John Peel". Metcalfe was at once struck by its adaptability as a capital hunting song. Later he went to Mr.Lattimer's residence, at Holme Head, and took down the music from Mr.Lattimer's singing. He then, after considerable research, found the music of the Scotch "rant" "Bonnie Annie" which was in Grave's mind when he wrote the song, and from that air Metcalfe composed the tune as it now exists.
[end quote]