Ah, not handcuffs proper, they are ‘persusaders’ or ‘come along’ cuffs.
The bit sticking up in the air was like a clip functioned by a mechanism they are holding in the other end in their hands. Hence you can see a gap at the apex of the clip and in the picture of a pair below by Hiatt, a once famous Birmingham manufacturer of law enforcement restraints.
Functioned like pair of talons gripping around a miscreant’s single wrist, with which the Constable could then “persuade” or plan drag them off into custody!
Great picture. Those mutton-chops on the seated chap to the left are ferocious!!
Cheers……John