Thanks for the pointers! I tried copying over the transform and orientation values from the UE default mannequin one by one, but it was a super slow, error prone process. I messed it up a few too many times, but the fingers were getting distorted as that process went on.
Both the character and the animations are bought externally, so I expected better in parts, but it’s OK. This model wasn’t going to be the playable character anyway, and a combat NPC only looking OK in combat isn’t an issue anyway 
I might look into re-posing the character, but my art or rigging skills are pretty non-existent currently. I have a feeling someone on the project will have to pick it up sooner or later anyway though!