Gilmour wanted three instruments. Ezrin brought a chart.
In January 1979 Pink Floyd moved into Super Bear, in the hills above Nice, and started seven months of work on The Wall. David Gilmour already had a piece of music from the sessions for his first solo album, cut in the same studio in 1978. It had no lyric. Once Roger Waters put words on it, the working title was The Doctor. The scene in the lyric is a real night: the Spectrum in Philadelphia, 29 June 1977, on the In the Flesh tour. Waters had stomach cramps so bad he thought he could not play. A doctor gave him a shot. He did the show barely able to raise his arm, and he later said those were the longest two hours of his life. The hands like two balloons, the pinprick that will keep you going through the show: that is the Spectrum, handed to a fictional singer named Pink.
Gilmour heard a bare song: bass, drums, guitar. Bob Ezrin, brought in to co-produce with Waters and Gilmour, heard an orchestra, and Waters sided with him. Michael Kamen wrote the chart. In September 1979, players drawn from the New York Philharmonic and the New York Symphony recorded it at CBS Studios on 30th Street. The band was not in the room. The row did not stay polite. By the accounts that have stuck, it ended in a restaurant in North Hollywood. The compromise is what you hear: Ezrin’s strings carry the body of the song, and Gilmour’s last guitar solo is left alone, with no orchestra under it. He cut that solo through his Hiwatt amps and a Yamaha rotating speaker, several passes, then kept the phrases that held.
Waters sings the verses, the doctor at the door. Gilmour sings the chorus, the man who has gone numb. Nick Mason is on drums, Waters on bass, Richard Wright on Hammond and electric piano, Gilmour on the Prophet-5 as well as the guitars. The Wall came out on Harvest in Britain on 30 November 1979 and reached No. 3. Columbia issued it in the United States on 8 December and it went to No. 1. Comfortably Numb was not the single. Another Brick in the Wall, Part 2 was, released on 23 November with One of My Turns on the B-side. This song simply sat on the double album, and it is the one audiences asked for anyway.
Comfortably Numb, which Dave saw as a more bare-bones track, with just bass, drums and guitar. Roger sided with me. So Comfortably Numb is a true collaboration: it’s David’s music, Roger’s lyric and my orchestral chart.
(Bob Ezrin, Guitar World)

On The Wall tour, from Earls Court in August 1980 through Los Angeles, Dortmund and the return to Earls Court in 1981, Gilmour played the solo from the top of the cardboard wall. The song closed the Live 8 reunion in Hyde Park on 2 July 2005, Waters and Gilmour on the same stage again. In January 2004 Scissor Sisters released a disco reading as a single. It peaked at No. 10 on the UK singles chart and No. 1 on the UK dance chart. Gilmour and Mason said they liked it. The record lost a Grammy nomination for Best Dance Recording to Britney Spears’ Toxic.
The argument is still in the mix. You can hear the three-piece song Gilmour wanted in the way the last solo is stripped, and you can hear Ezrin’s chart in everything that comes before it. Waters got his doctor. Gilmour got the last word, and it is a guitar.