Take a look at Tommy Shelby, played by Cillian Murphy and you’ll notice he usually wears his pocket watch suspended from a single chain, in the left pocket of his waistcoat. This is an example of the “Single Albert”.
Arthur, played by Paul Anderson, however, sometimes sports what’s called a “Double Albert” — which is to say he wears a double chain with the watch in one pocket and a fob in the other.
In both cases, the watch chain features a t-bar which fits through a buttonhole to secure it. You might even like to hang a fob from the t-bar itself — typically this would be some sort of medallion, perhaps with your initials engraved.