Green’s Dictionary of Slang

1. to the account of.

1885

Bulletin (Sydney) 28 Feb. 13/4: That furnishes us with a key to the Lara-like gloom which overshadows the proprietor of a free-lunch bar, when a Knuze scribe cheerily remarks, ‘put that glass o’ rum down to me,’ and then proceeds to wrap himself round the corned-beef sandwiches.

2. the responsibility of.

1961		T. Taylor Baron’s Court All Change (2011) 111: [I]t was all down to her in the first place that I made friends with Harry.
1970		‘Metropolitan Police Sl.’ in P. Laurie Scotland Yard (1972) 322: down to: thus: X is down to Y = X is Y’s responsibility.
1977		G.F. Newman Villain’s Tale 34: ‘What’s he do, Mickey?’ ‘Armed blags is what I hear – s’posed to be one or two nice little tucks down to him what he didn’t go for.’.
1989		in G. Tremlett Little Legs 105: That was down to the Krays.
1992		in R. Graef Living Dangerously 89: If I bring you a ring and say it’s gold and you believe me, it’s down to you.
2001		K. Sampson Outlaws (ms.) 22: I never seen her in there after that. I think that was down to Derek.