@futurebird On the basis of the context for this statement you provided in another reply, personally I wouldn't bother to include the 'done' in my reply either.

"He would not agree, even if he had."

@futurebird "In hospital" - not "he is in the hospital", but "he is in hospital". I'm always listening for other places that are states of being in UK English, but I've only heard hospital. Also, in the US we can be "in college" but in the UK you can be "at university".

@futurebird Learning Swedish perhaps gives me an insight I might not otherwise realise, as a native Old World English speaker (Ireland, UK, South Africa).

In Swedish we have the supine tense, which modifies the second verb in this construction your showing here:

Jag har gjört = I have done. Gjört is göra in the supine, and göra means to be. It seems correct also to say Jag här gjört det, too, though. The point being that in Swedish it's formally defined as a tense in this way, with its own verb modification system. So I guess the UK English construction feels a little more intelligible to me from seeing how it works in a closely related language!

@futurebird it makes me think of of a typical Latin grammar; I have read in many places that the most common word order in Latin is subject, object, verb. Of course that may be because it's the first word order they teach in a typical Latin textbook; other word orders were used. English, on the other hand, more often ends with an object, at least when spoken by the plebs. It's as if there's a desire among the educated to remind listeners "I took Latin, if you would care to recall!"

@futurebird he would not agree, even if he had agreed?
believe you me, getting the subtleties of meaning in English is sometimes really hard as a second language learner.
It's driving me all but crazy*

(*still having a hard time fully grasping this idiom)

@futurebird is present here in Australia too