So it turns out that conductive epoxy is a thing. And you can get capacitors which can be glued into circuits.
It also turns out that those capacitors can't be soldered with solder paste. Guess how we know.
@amcewen ooof thats a harsh lesson.
@concretedog luckily the assembly house spotted it before they fitted them to 100 boards, so it was just a frantic 10 minutes or so to source something else to free up their pick-and-place line
@amcewen Thats a pretty good result in the end... could have buggered up the boards!