A MET Police chief said he watched helplessly from a locked car as PC Keith Palmer was murdered by a terrorist.

Deputy commissioner Sir Craig Mackey said he stayed in his chauffeur-driven car as nobody with him had protective equipment or a radio.

He was about to be driven out of Parliament after a ministerial meeting when Khalid Masood fatally stabbed PC Palmer, 48, in March last year.

Masood, 52, had also driven into and killed four people on Westminster Bridge.

He was shot dead by armed police.

Sir Craig told an inquest into the killer’s death he heard a loud bang then saw Masood looking like “a clear threat”.

A colleague in the car locked the door, then Sir Craig saw the terrorist carrying “a butcher’s knife”, which he used to repeatedly stab PC Palmer with in a “very determined” way.

After hearing the shots that killed Masood, Sir Craig said he tried to leave the car but a cop told him to stay. He added: “It was the right thing to do.”

The inquest at the Old Bailey continues.