Thanks folks

The brown cloak works really well 
Bloody printer!

But with hindsight I prefer the more subdued colours

Did you superglue the entire surface or did you just spot glue it along the edges? Curious what would stay clearer over time.
The glue went onto the ink side - the rough side - of the acetate and I absolutely flooded it before pressing on the pre-prepared frame and glass. The excess - a lot of it - and any air bubbles were squeezed out. So in answer to the question, it was the entire surface. I’ve no idea on the longevity of this approach, though I’ve managed to get superglue over the glass of most of the other windows in the project, which has stayed clear so far. The slaughterhouse glass was glued over 2 years ago and is still clear, so fingers crossed.