Thanks for the quick replies!
I found the two 19mm adjusting nuts and wound them out so the locking but was flush with the end of the thread, then bang, the brakes came off! I'd say there's a touch of rust in there somewhere from lack of use, as it had been sitting for about 2 or more years in a shed
Will look into new brake linings for it, was quite daunting coming up to a roundabout pumping on the brakes and nothing happening, good thing it has a handbrake!