Yeah, it wasn’t. I should really post this in the litany of dumbassery thread… 
I’m not really sure how anything made a noise and didn’t pop on previous steps, as I had the breadboard round the wrong way, in an effort to align it with the diagrams. All would have been fine if I’d also turned the power header round too, so I was sending -ve into +ve… 
I have forgotten pretty much everything I learned last winter.
Edit: It also looks like I’ve blown at least the TL074, so have replaced both chips just to be sure.