An Albert, named after Prince Albert, is a security chain usually of gold, or could be silver, that has a bar on one end to fix through a button hole and a clip on the other that hooks through the loop on the pocket watch of the same metal as the chain.
The bar was put through a hole on the wearer's right and the chain loops across, under the top coat, to the watch pocket.
The two gentlemen in flat caps have them; the older gentleman appears to have a tassle? bunch of keys? hanging on a chain to just under the head of his stick.
Watermusic