Leon McCaskre died after being hit by the vehicle in Maida Vale.

The collision happened moments after McCaskre stabbed his ex-partner, Yasmin Chkaifi, to death in the street.

Detective Chief Inspector Neil Rawlinson said: "Having reviewed the CCTV evidence and taken statements of numerous members of the public and attending officers, as well as reviewing the legal position regarding self-defence and defence of another, a decision has been taken that the driver of the car, a 26-year-old man, will face no further police action.

"He is considered a vital witness to our investigation and will be offered support from professionals to help him come to terms with the terrifying situation he was confronted with."