Green’s Dictionary of Slang

la-di-da n.

2. ()

a.1885		N. Power in Booth Pink Parade (1933) 145: How d’you like the La di Da, the toothpick and the crutch? / How did you get those trousers on, and did they hurt you much?
1898		R. Batchford Tommy Atkins of the Ramchunders 268: An’ ’ow do yer like the lardy da / With ’is toothpick and ’is crutch? / An’ ’ow do yet git yer trousers on,/ An’ do they ’urt you much?