The failure led to more than 2,000 flights being cancelled and hundreds of thousands of passengers affected.

It is the first time MI5 has confirmed the BBC's revelation that it gave evidence based on lies in court while defending the violent informant.

Nicholas Brandram's sisters tell the BBC he did a DNA test to speed up the inquiry but never got the results.

The trust's new chief executive says he apologises unreservedly - "What happened was utterly unacceptable."

Sulaiman Tajzai travelled from Leeds to London, where he stabbed his victim with a kitchen knife.

She was best known for playing the character Dr Beatrice Mason in the 1980s BBC wartime TV drama