Records show that Hyde Park was monitored daily

In 1962, 61 cases of prostitution, 181 of indecent behaviour and 27 of "male importuning" were reported in the central London park.

Illicit activities in London were also common on Primrose Hill and in St James's Park, according to park authority records.

The records are on show at the National Archives in Kew.

The Archive Awareness Campaign encourages the public to take advantage of files that span 1,000 years of British history.

For God's sake get this mess cleaned up An outraged schoolteacher

They show the authorities kept a record of what happened in London parks and in particular Hyde Park, which was monitored daily.

According to the records one outraged schoolteacher wrote to the home secretary in August 1961, saying: "For God's sake, get this mess cleaned up.

"And insist on park keepers to do their job and clear away this public offence and indecency. Otherwise they are just open-air brothel keepers."

Katie Norgrove, policy and development officer at the National Council on Archives, said: "Everything you ever wanted to know about indecent behaviour in London's green bits is in this file.

"And the complaints made by members of the public illustrate the outrage people felt at these outdoor exploits."