The prime suspect in the murder of Yvonne Fletcher could finally be questioned under oath after a civil action was mounted against him in the High Court, The Telegraph can disclose.

Lawyers acting for John Murray, a former colleague of WPc Fletcher, served civil proceedings papers on Saleh Ibrahim Mabrouk, a close aide to Libya's former dictator Muammar Gaddafi, this week.

The civil case could see the Government being forced to disclose evidence in the case against Mr Mabrouk which it refused to release to Scotland Yard in 2017 on grounds of national security.

The news coincides with the 35th anniversary of the murder of WPc Fletcher, who died in a hail of bullets fired from the former Libyan embassy in St James’s Square, central London on April 17, 1984.