Green’s Dictionary of Slang

worker n.1

[work v.]

1. a criminal; usu. in combs. such as badger worker under badger n.1 , charity worker under charity n., dunnigan (worker) under dunnaken n., lush worker under lush n.1 , skin worker under skin n.1 , tail worker under tail n.

[UK]G. Ingram Cockney Cavalcade 256: ‘Finger-prints!’ the detective said in contempt. ‘No. It was too good for most of those that do that sort of job. That’s why I thought you might know something about it. You’re such a pretty worker.’.
[US]Q. Reynolds Police Headquarters (1956) 77: Bonwit Teller has had a series of pocketbook robberies. The character who is getting away with these bags [...] goes into the ladies room [...] ‘Toilet workers — Female.’.
[UK]‘P.B. Yuill’ Hazell and the Three-card Trick (1977) 78: You take a real worker — one ov the fanny mob or a cracksman or even a dip, anybody wiv a bit ov class, he’ll tell yer.

2. in a pickpocket team, the member who actually picks the victim’s pocket.

[UK]W. Sickert New Age 19 Mar. 631: All these he would carry with him so that he, the ‘worker,’ or the ‘tool,’ might have his mind and his hands freed for the masterstroke.

In phrases