Green’s Dictionary of Slang

bagman n.

[SE bag, whether of samples or possessions]

1. [mid-18C+] (also bagsman, bagster) a commercial traveller.

2. [19C] a second-hand clothes street dealer.

3. [mid-19C] (Aus. und.) a sneak-thief.

4. [20C+] (Aus./US) one who collects or administers the collection of money obtained by various criminal activities [bag n.1 (2c)].

5. [20C+] (Aus.) a bookmaker [bag n.1 (2)].

6. [1910s+] (Aus.) a tramp who travels on horseback; thus bagman’s leg, the loss of a leg through falling under rolling stock; bagman’s union, the brotherhood of travellers.

7. [1950s+] (orig. US) a messenger, a go-between, esp. one who conveys a bribe from the one who offers it to the one who accepts.

8. [1960s+] a major narcotics dealer, i.e. one who has ‘the bag’ [bag n.1 (6b)].

9. [1970s] (Aus. Und.) in a shoplifting team, the person who actually takes the targeted object.

10. [2000s] (orig. US) in fig. use of sense 5, an employee, a menial, esp. one who takes the blame for the decisions and activities of their employer.

In compounds

bagman’s gazette, the (n.)

1. [1900s] (Aus.) the Worker newspaper.

2. [20C+] (Aus.) gossip and rumour, reified as an imaginary ‘newspaper’ and 'distributed’ by travelling salesmen.