A businessman has told how he probably missed facing the Westminster terrorist by 10 minutes.

Dover -based John Shirley had been travelling to Parliament that afternoon and would have used the entrance where PC Keith Palmer was stabbed to death.

But Mr Shirley was stopped in his tracks 500 yards away by security officers as the area began to be sealed off.

Mr Shirley, 54, who lives in Bridge, told Kent Online: “I had a narrow escape. Had I arrived 10 minutes earlier I may have come across the terrorist.”

Mr Shirley, who is also chairman of the Canterbury United Nations Association, had been heading for a UN seminar at the House of Commons.

He had taken the train from Dover Priory to St Pancras International and cycled from there when he was stopped at Whitehall.

He said: “Suddenly I heard the blast of a siren and an unmarked car with flashing blue lights pulled up.

“Two men dressed in black got out and put on what appeared to be flak jackets. One waved at my line of traffic to turn left.

“Eventually I went along the Embankment and saw more and more armed police who were turning coaches back.

“I stayed for 10 to 15 minutes to see if they would lift the cordon because nobody knew yet what had happened.

“I asked police officers and they would only tell me that there had been an incident.

“Had I arrived 10 minutes earlier I would have been in the thick of it.

"I would have used the entrance where the police officer was stabbed.

“I had no cause to use Westminster Bridge that day but I have cycled over it before and as a cyclist I am always worried about someone using their car as a weapon.

"Obviously it is a lethal weapon in the wrong hands."

Mr Shirley says now his thoughts are now with the families and friends of the victims.

The terror maniac had mown down pedestrians at Westminster Bridge at about 2.40pm on Wednesday , killing three.

He then drove on, crashed his car into railings at the Houses of Parliament and stabbed unarmed PC Palmer before armed colleagues shot him dead.

Mr Shirley runs a freight forwarding business in Dover, John Shirley Limited, at the The Old Harbour Station in Elizabeth Street.

The seminar, which was inevitably cancelled, was to be run by Adama Dieing, the UN Secretary-General’s Special Adviser for the Prevention of Genocide.

The meeting had been scheduled for 4.30pm but Mr Shirley intended to arrive unusually early to allow time for routine security checks.