E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
To go by beggars bush, or Go home by beggars bushi.e. to go to ruin. Beggars bush is the name of a tree which once stood on the left hand of the London road from Hunting don to Caxton; so called because it was a noted rendezvous for beggars. These punning phrases and proverbs are very common.