Albert, without taking his eyes of your 'customer', says "It appears this man is a couple of shillings short. Could you..." - he pauses for added drama - "...take him outside please, Hugo?" The would-be con man is clearly unnerved at this prospect and stutters "No, wait! I mean, issan 'onest mistake, really! Surely we can work something out?!"
You've been playing this game before, and surprisingly often it results in the victim realizing that they do seem to be carrying enough money after all. Since it's starting to look like this isn't going to be the case this time, Albert is probably going to ask you to take this man to the Constabulary at the other end of Woolstone Road.
"Well, what do you suggest, then?" he asks the swiftly shrinking man. When no useful reply is forthcoming, the barkeep points at the chain hanging from the man's breast pocket and says "Let's see what you have right there, shall we?" The man, realizing any protest is going to be pointless, takes out his pocket watch and hands it to Albert. Albert has a good look at the thing and says "Right, it's your call: either I keep this in payment for our services, or Hugo here hands you over to the Watch in a bit. What'll it be?"
"Alright, keep the bloody thing!" the man shouts, and starts to turn around. This is generally the cue for the bouncer to make sure dramatis personae exit the stage without further hassle.