Source.

While emojis like 👍 and ❤️ have partly relieved us of the necessity to create new verbal expressions for approval, one may feel a certain nostalgia for bygone expressions like spiffing, ripping, top-notch, hunky-dory, and tickety-boo.

While the quaintness of such jovial expressions harks back to a broader class-base than the world of Jeeves and Wooster, I suppose they are now usually heard on the lips of a rather educated latter-day generation, with varying degrees of post-modern irony—including both rabid bendy-banana nostalgists and the “Guardian-reading tofu-eating wokerati”. 

The origin of tickety-boo is unclear. Though there doesn’t seem to be a written example before 1939, it appears to go back at least to the early 1920s—probably RAF slang, perhaps a combination of “that’s the ticket” (early 18th century) and “peek-a-boo” (or at least “boo”).

But there’s also a suggestive derivation from Hindi ṭhīk hai, bābū, “it’s all right, sir”. * This would make it one of a whole host of words adapted from Indian languages, popularised by way of the British empire (cf. Hidden heritage).

This elliptical first draft for a film script conjures up a picturesque gathering, setting the scene before introducing the host and his guests, their sporting pastimes followed by a sumptuous buffet:

Dinghy and catamaran on atoll; loot thug in choky. Cushy veranda of jungle bungalow (lacquered teak, calico palanquin, juggernaut; chintz cot, patchouli): Blighty mogul (mandarin) in pukka cashmere pyjamas.
[The guests arrive:]
Lilac cummerbunds (doolally!), khaki dungarees, pashmina (shawl), bangles with bandanas. Jodhpurs for polo and cheetah gymkhana.
Tiffin (kedgeree with chutney) and tank of punch; candy and cheroot—tickety-boo!

Cf. the Venetian language, Some unlikely Turkish vocabulary, and The kiosk in Turkey and Europe. And do relish Nicolas Robertson’s remarkable anagram tales! The linguistic reversals of Armstrong and Miller are also very drôle—see Textual scholarship, OMG.

* An alternative derivation from French, offered in the wiktionary entry, is also attractive: ce que t’es beau (“how beautiful you are”). Cf. “toodeloo”, said to be a corruption of tout a l’heure—even more quaint is toodle-pip.