Their memorandum, from 1909, describes pickets at the House of Commons as “half-insane women” who intended to commit acts of violence.

It includes an investigation report from Special Branch at New Scotland Yard that identifies one of the suspects as “a little woman wearing a tam-o’-shanter”. The documents were released yesterday by the National Archives at Kew.

The Home Office memorandum, which discusses whether the pickets should be removed, reveals that threats were made to Herbert Asquith, the Prime Minister. It says that “there is now definite ground for fearing the possibility of the PM’s being fired at by one of the pickets at the entrance to the House”, and that the women were planning “something nearly amounting to a conspiracy to murder”.

The report toys with the idea of forcibly removing the pickets, who had been in place for eight weeks, but concludes that this would be impossible without revealing the threat to Asquith’s life.

“The whole matter would have to be thrashed out in court . . . We should have to make known the facts leading us to believe there is a conspiracy to murder the PM.

“The prominence which would be given to this in the press would probably act on the minds of these half-insane women, and might suggest effectively the commission of the very act which we wish to prevent.”

The memorandum concludes that “the safer course is to leave the pickets alone for the present and redouble the police precautions”.

It was prompted by a police investigation into allegations made by a Mrs Moore, a friend of Asquith’s sister-in-law, who told detectives that “certain suffragettes have been practising shooting at 92 Tottenham Court Road”. She said that she knew at least five women who “had given expression of their intentions to commit acts of violence”. These women had been picketing the Houses of Parliament but Mrs Moore refused to name them, because it would be a “breach of faith”.

The police report continues: “I made inquiries at 92 Tottenham Court Road and the proprietor of the miniature shooting range there informed me that, about three weeks ago, two women (one of whom he described as a little woman wearing a tam-o’-shanter) who were said to be suffragettes, had been practising with a Browning pistol. I asked him to inform police if they should visit there again.”

Explore UK News

• Crime News

• Education News

• Health News

• Science News

• Scotland News

Times Recommends

• Third of Muslim students back killings
• Curfew tames feral yobs of Cornwall
• £3,000-a-month drug free abroad