'Tickety-boo'. - tikai babu and the Raj, maybe?

A late entrant for 'tickety-boo'. I agree with the correspondent who suggests that 'thik hai' is one part of it.
However, consider that there were Indian troops in the trenches in France during at least 1914-1915. Here, the British Army certainly mispronounced the French 'beau', meaning, 'well','good' or even 'ok', as 'boo'.

While I have nothing better than a suspicion for this contention, could it not be that 'thik hai?' - with response 'boo', could conflate as 'tickety-boo' ?

Regards, Bryan McEnroe.

The earliest written usage apparently dates from 1939, though Partridge claims the phrase was known and used in the 1920.

The Hindi phrase which he transliterates as "tikai babu" means "everything's fine, sir", and despite the lack of documentary evidence for the phrase being around pre-1900, this does sound quite likely as the source.