London Bridge: Steve Marsh relives 2017 Westminster Bridge attack
Friday's stabbing attack at London Bridge, in which two people were killed, has brought back difficult memories for Steve Marsh.
The former Metropolitan Police officer, from Llantwit Major, Vale of Glamorgan, recalls seeing his colleague PC Keith Palmer killed by Khalid Masood at the House of Commons almost three years ago.
On 22 March 2017 Steve Marsh found himself at at the centre of a terrorist attack in London.
Four people were killed and at least 50 people were injured when Khalid Masood drove his car into crowds on Westminster Bridge.
He then got out of his vehicle outside Parliament and stabbed PC Keith Palmer to death before being shot dead by police.
Mr Marsh, who was positioned on the gate at the House of Commons, said he first realised there was a problem when he heard a loud bang and saw lots of people running towards him.
'He's stabbing people'
"My first reaction was to try and establish what they were fleeing from," he told Gareth Lewis on BBC Radio Wales.
"I remember shouting to people 'what have you seen? What's happening?'
"I remember there being one female voice responded saying 'there's a man, he's stabbing people'."
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At that moment Mr Marsh turned around and saw his colleague PC Palmer being attacked.
"I back-tracked through the gate at Parliament and that's when I've seen PC Keith Palmer being driven backwards by the suspect with a large carving knife in each hand, with a stabbing action down on my colleague and driving him backwards."
He watched as a pair of armed close protection officers ran past him and shot Masood.
After the incident Mr Marsh was given leave but he turned down an offer of counselling: "All the support was there, we had welfare officers in the police and the calls were pretty quick to come in from them.
"From my own perspective I never needed them.
"I've got good friends and a good large family so I always had someone to talk to.
He said his almost three decades in the police had left him "somewhat conditioned for what happened".
"I've never seen anything like that happen before but I've seen varying degrees of it.
"I've seen injured people, I've seen stabbed people so it didn't come as much as a shock to me as it might have done."
Friday's attack has prompted calls for large venues to have a terrorist attack plan, but Mr Marsh is not convinced that would work: "I'm a bit cynical about such things," he said.
"No one attack is the same as any other. You never know where it's going to come or what shape it's going to come - I don't see how you can make plans for that.
He also doubts people caught up in a sudden attack would follow a plan: "In my experience it's rare that people follow the plans - you have little to no time to react most of the time and so to expect people to follow any kind of plan I think is a bit of a tall order."
"Most of these attacks come pretty suddenly, it doesn't give you a chance to react sensibly - you just do what you do."