The Opie's in 'The Oxford Dictionary of Nursery Rhymes' give 1675 as the date of the move of Old Bethlem Hospital from Bishops Gate Without' to Moorfields (a little west of Bishop's Gate Street Without). This is considerably later than the song "Tom O'Bedlam". On a map of 1731 we find Moorfields with the alternative label N. Bethlem. The Opie's statement is in notes to "As I was walking o'er little Moorfields", closely related to "Tom-Tell Truth". They note "A shoulder of mutton jumped over from France", but say nothing about how Bedlam jumped over the Thames. When did that happen?