Fit the pads with one of the 12mm bolts completely undone, so the caliper swings 180' on the other 12mm bolt.
Once the pads are snug in the correct position, the caliper can be swung 180' into position, tapped with a bit of 4x2 until the 12mm bolt lines up, then hold the bigger nut (14mm?) and tighten the 12mm bolt.
I will post photos of open and closed next week when I can reduce the file size of the photos I took to upload them on here. Max file size 1Mb.