Green’s Dictionary of Slang

Wood, the n.

St. John’s Wood, London NW, a suburb often chosen by men to house their mistresses .

[UK]Sporting Times 7 Feb. 3/3: The life’s so dull, so slow, so beastly good, / I must return to Brompton, or the ‘Wood’.
[UK]Illus. Police News 30 Dec. 6/4: When a chap ain’t as a slow as a funeral hearse, / And runs a dear friend in ‘the Wood’.