Green’s Dictionary of Slang

writing, esp. office work; thus push a pen v., to perform office work.

1887		Daily Bulletin (Honolulu) 26 Feb. 2/1: Decent, respectable young men, thoroughly competent as accountants and book-keepers [...] They had been brought up to pen-driving, and nothing else.
c.1896		Tom Clare [perf. ] ‘Absolutely Wrong’ 🎵 How on earth do those poor blighters manage / Who sit on stools and push a beastly pen?
1899–1900		C.L. Cullen Tales of the Ex-Tanks 235: I went back to the office to tell ’em I was too strong for pen-pushing any more.
1911		‘Sing Sing No. 57,700’ My View on Books in N.Y. Times Mag. 30 Apr. 5/4: The Three Musketeers Alexander Dumas [...] when he got to pushing the pen across the paper he got down to cases right away.
1924		‘Digit’ Confessions of a Twentieth Century Hobo 26: ‘What is your line of business?’ ‘Any old thing from pen-pushing to handling a shovel.’.
1936		D. Burley in Chicago Defender 7 Mar. 11: Jones is the most outstanding menace, we of the pen-pushing craft have, to the dinner plate.
1936		‘George Orwell’ Keep The Aspidistra Flying (1962) 51: What boy wouldn’t dread it? Pen-pushing in some filthy office – God!
1952		J. Jones From Here to Eternity (1998) 570: I dint know you ever pushed a pen, Prew.
1965		R. Graves in Richards Old Soldier Sahib (1965) 3: Frank [...] wrote that he found pen-pushing a wearisome occupation.