The 2,500 lawyers who responded to a survey by Legal Cheek reported finishing times of 11.28pm at Kirkland & Ellis, 10.51pm at Ropes & Gray and 10.17pm at Weil, Gotshal & Manges.

Kirkland associates clocked off at 9:46pm on average in 2020. The longer working day corresponds to a deals bonanza for firms: Kirkland advised on 58 deals worth $19 billion in the first and third quarters of 2021.

Lawyers, however, are suffering from burnout, prompting firms to pay ever greater sums to retain talent.

Charlie Geffen, former corporate chair at US law firm Gibson Dunn, said: “The market is white hot at the moment and law firms are not normally configured for this level of activity. But it won’t last.

“There are lots of examples of periods like this, for example before the global financial crisis and the dotcom crash . . . Late nights have always been a function of deal activity.”