Jack Maher (played by David Calder) is the Head of Security for Moores Bank and before that he was in the Fraud Squad for 19 years. He appears with "Cops and Robbers".
He is thrilled at taking on the best grifters in Europe and out-grifting them- having already had an undisclosed encounter with Albert-, known for playing on their weaknesses; Maher is regarded by Albert as the sole exception to the rule that there is always a way out of the traps others set. He tries to force the crew into catching known bank robber Sam Richards, who had already broken into the other branches of Moores' in other cities, by blackmailing Mickey with video footage of Danny from an occasion where he acted as lookout man for a casino robbery in his youth, knowing that Mickey would take the job due to both his loyalty to his crew and his ego causing him to hope that he could get the better of Maher.
Although he easily anticipated Mickey's attempt to break into the bank to get the tape of Danny, Mickey quickly began to turn against Maher when he learned that Richards simply wanted to recover a diamond that had belonged to his now-deceased father, particularly when Albert realised that Maher- his reputation increasingly damaged by Richards' easy infiltration of the other banks- intended to catch Richards and Mickey simultaneously to prove himself.
When the theft took place, Albert went straight to the security centre of the bank to receive the tape from Maher after the cameras showed Mickey and Richards at the vault, only for smoke to obscure the cameras as Maher watched; by the time he and his team got down to the vault, the two thieves had vanished despite the locked door between them and freedom. Although he realised that the team had rerouted the camera feed, Maher was so occupied working out what had happened that he failed to prevent Stacie and Danny- disguised as security guards- from infiltrating the real vault to recover the diamond while he was busy trying to find the source of the fake video feed. As a final joke, Mickey and the gang arranged for a woman to sing opera outside Maher's window after the theft had failed, reflecting Maher's earlier comment that "It's not over until the fat lady sings".