Green’s Dictionary of Slang

tail v.

1. to have sexual intercourse with, to work as a prostitute.

[UK] in Weis & Pottle Boswell in Extremes (1971) 248: When we talk of pleasure, we mean sensual pleasure. When a man says he had pleasure with a woman, he does not mean conversation, but that he tailed her [OED].
[UK] ‘My Shickster Molly’ in Knowing Chaunter 43: I care not for pals tho’ they call me C. P., / ’Cause my shickster Molly goes tailing for me.
[US] in G. Legman Limerick (1953) 92: A convict once, out in Australia, / Said unto his turnkey, ‘I’ll tail yer.’ / But he said, ‘You be buggered, / You filthy old sluggard, / You’re forgetting as I am your gaoler.’.
[UK]‘Walter’ My Secret Life (1966) II 317: Molly was astonished. She had never been tailed in that attitude before, I am sure.

2. to follow, to keep under (police) surveillance.

[Aus][A. Harris] (con. 1820s) Settlers & Convicts 258: Thus it becomes neccessary to keep a man after them [i.e. cattle on the move] all day in the bush, till they settle, which is called ‘tailing them’.
[Aus]Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 153: TAIL [...] to follow or spy upon, to keep under surveillance.
[Aus]L. Stone Jonah 132: Wot makes yer tail up after me?
[US]J. Lait ‘If a Party Meet a Party’ in Beef, Iron and Wine (1917) 97: He waits around till I get off and tails me on that car, and takes a seat acrost from me and gives me the all-over like he was gonna buy me or something.
[US]J. Black You Can’t Win (2000) 227: You ‘tail’ him to a genteel-looking place with a ‘private board’ sign in a downstairs window.
[Ire]Eve. Herald (Dublin) 9 Dec. 4/6: ‘Taill’ [sic] means that a crook is being watched by detectives.
[US]R. Chandler ‘Red Wind’ in Red Wind (1946) 29: I tailed him home from headquarters.
[US]Mezzrow & Wolfe Really the Blues 90: Zigzagging all around town to make sure we weren’t being tailed.
[US]B. Schulberg On the Waterfront (1964) 24: He spotted Sonny tailing him.
[US]N. Heard Howard Street 233: We’ve been tailin’ you ever since you left the hospital.
[US]G. Swarthout Skeletons 42: I was followed by a patrol car. I think they use ‘tailed’ in crappy crime novels.
[US]Pileggi & Scorsese Goodfellas [film script] 103: I’m sure we’re being tailed.
[US]C. Hiaasen Lucky You 137: He insisted he would have noticed somebody tailing them from the restaurant.
[US]C. Hiaasen Nature Girl 27: You want me to keep tailing your husband?
[Aus]L. Redhead Thrill City [ebook] ‘Maybe he was following me, saw you, and became fixated?’ [...] ‘That’s not a reason to have my family tailed’.
[US]J. Ellroy Hilliker Curse 14: He told me he had private eyes tailing my mother.

3. to make the object of a criminal plan.

[US]J. Archibald ‘Time Will Tell’ in Phantom Detective Sept. [Internet] This ain’t a bank ya’ve got tailed, is it, Bat?

In derivatives

tailer (n.)

(US und.) a bodyguard who accompanies the transporter of valuable goods.

Jackson Dly News (MS) 1 Apr. 7/3: Crook Chatter [...] ‘A tailer is one who accompanies the carrier of valuables to afford him protection’.