Senior figures in Downing Street were calling in 2016 for the SAS to have its “wings clipped” as it emerged that a growing number of suspected murders of Afghan civilians were being investigated by military police.

Critics of the elite unit’s behaviour were led by Jeremy Heywood, who at the time was cabinet secretary to the then prime minister, Theresa May, according to a memo cited last week during a public inquiry into allegations of unlawful SAS killings in Afghanistan.

The note, written by the head of Britain’s military police, David Neal, in September 2016, records there were “no shortage of detractors” in Whitehall of SAS conduct, amid direct criticism from other senior officials.

The previous day, Neal had met Stephen Lovegrove, the most senior civil servant at the Ministry of Defence (MoD), who warned he was “troubled” by a culture within Britain’s special forces.

The barrister went on to argue that the inquiry, chaired by Lord Justice Haddon-Cave, needed to establish whether military police investigations “may have been tainted by political pressure and improper interference”.

However, two legal challenges on behalf of victims’ families and investigative journalism by the BBC and others led to the release of internal MoD material that persuaded the former defence secretary Ben Wallace to commission a public inquiry, which is continuing.

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