Between July 2018 and June 2019 there were 1.58 million people processed by the system, compared with 1.86m in 1970, data from the Ministry of Justice show.

The number sent directly to jail when sentenced, 75,800, was the lowest proportion for a decade – at 6.5 per cent.

Prime Minister Boris Johnson has said he intends to build more prison cells and increase sentences for some offenders.

Critics, however, argue that the proposals run contrary to a substantial body of evidence supporting a rehabilitative approach to criminal justice.

About 1.37m defendants were prosecuted in the past year, with those in the magistrates’ courts down two per cent.

But the average length of a prison sentence has risen to 17.4 months, the highest in the past decade. The average term has increased since June 2009, when it was 13.5 months.