"A Quick One, While He's Away" is a 1966 medley written by Pete Townshend and recorded by The Who for their album A Quick One. The song also appears on the album BBC Sessions. In the performance on their Live at Leeds album Townshend calls the 9 minute "epic" track a "mini-opera" and introduces it as "Tommy's parent". This song tells the story of an unnamed girl who is left stranded by her lover "for nigh on a year." Her friends inform her that they "have a remedy"; the remedy comes in the form of Ivor the Engine Driver (the British term for the operator of a railway locomotive). When the lover returns, the girl confesses her infidelity, and she is ultimately forgiven.

The song has six distinct sections. The brief harmonized a cappella intro is titled "Her Man's Been Gone". The "Crying Town" section is sung by Roger Daltrey in an atypical low register. Daltrey also sings "We Have A Remedy" in his more usual voice. John Entwistle plays "Ivor The Engine Driver" in that section. Then comes "Soon Be Home", another harmonized section. Finally, "You Are Forgiven" is sung by Pete Townshend -- his only lead vocal on the album (except, on most versions of the album, a small part of "Heat Wave").

This song is The Who's first publicized venture into the rock opera genre, although the song "I'm a Boy" was the result of Townshend's first delve into rock opera, entitled "Quads", and a precursor to their later, more ambitious project Tommy. A studio recording appears on their A Quick One album, and a live recording appears on Live at Leeds. Curiously, when the song was performed live, instead of "girl", Townshend and Daltrey would make a point to sing "Girl Guide". A video performance was made for The Rolling Stones Rock and Roll Circus, and can be seen on that video and on Jeff Stein's documentary film The Kids Are Alright. It also appears on both films' soundtrack albums. Another version recorded live at the Monterey Pop Festival can be found on the Monterey Pop Festival four-disk set and on another Who film, Thirty Years of Maximum R&B Live. A mixed studio and live version can be found on The Who's four disk set Thirty Years of Maximum R&B.

The section where the band repeats the word "cello" was done as a joke. The band wanted a string section to play in the song but Kit Lambert said that they couldn't afford it, so they just repeated the word where the cello was supposed to play. The Live at Leeds version of the song was used in the soundtrack of the movie Rushmore (though the Rock and Roll Circus version - specifically "You Are Forgiven" - was used in the film).

The song was rehearsed for inclusion in The Who's 2006/2007 North American Tour, but was not part of any set list.

Graham Coxon performed the song in late 2004 at the Queens of Noize Christmas Party.

My Morning Jacket performed a cover of the song at the 2006 Bonnaroo Music Festival and on several European dates during their stint as an opening act for Pearl Jam in the same year, when the latter's frontman Eddie Vedder would join them on stage. One such occasion (9/20/06, Duomo Square, Pistoia) is documented as a bonus track on the DVD version of the PJ concert film Immagine in Cornice.