Thanks, all.
The UKBEG spirit (which isn't 70% proof, contrary to what I believed
) got me the Superpower that is Ursus to help me to reclaim custody of my bikes but the keys have helpfully been put into a storage box.
Specifically, the keys have been put into one of around 100 storage boxes which are now in a lock up. Unfortunately, I didn't get told the keys were in one of the boxes until after I'd put all of the boxes into the lock up so they could be in the first box I open or they could be 30' from the door with 4 other boxes on top. Without the keys, I've got two very effective paperweights.
Look on the brightside. That's better than having the keys but no idea where the bikes are