Barrow's emergency services pay their respects as nation mourns slain police officer

Against the backdrop of a cloudy sky and fluttering in the spring breeze, the Union Flag was set at half mast outside Barrow fire station.

Crew members had wanted to pay their respects to PC Keith Palmer, the police officer slain by a terrorist in Wednesday's attack on Westminster, as floral tributes were left to him in the capital.

The move came as counter-terrorism detectives made efforts to trace any associates of Khalid Masood as they mounted a huge investigation to establish what triggered the terrorist's murderous rampage.

Watch manager, Jamie Coward said: "The flag is flying at half mast in honour and respect of our fellow emergency service colleague and members of the public who have been tragically affected by the events in London. Our thought are with the families of all those affected."

Yesterday, an American tourist shared a photo of herself with PC Palmer taken outside parliament, less than an hour before the officer's death.

Staci Martin, visiting from Florida, said she wanted to share the image for "people to know what a nice person he was and how fragile life can be".

Around 45 minutes later, Khalid Masood, formerly known as Adrian Elms, drove a car into a number of pedestrians on Westminster Bridge, before stabbing and killing PC Palmer, a 48-year-old father-of-two, at the gates to the Palace of Westminster.

Of the photo, Ms Martin told ABC News: "It's my first time in London and I see his hat and I'm like 'I have to take a picture of him with his hat'."

"I walked up to him and said 'do you mind if I take a picture?' He said 'no problem'. He was really nice."

She said she wanted to ensure the photo got back to his family, believing it must be one of the last photos taken of him alive.

Meanwhile, Barrow and Furness MP John Woodcock has told how he is determined that some good should come from the incident.

Along with other MPs, parliamentary staff, and visitors to Westminster, Mr Woodcock was held in a security lockdown for six hours before being released.

After reflecting on the experience and of the determination of the British public not to be cowed by the attack, he is leading a special push to connect the young people of Furness with parliament and democracy.

In a letter to headteachers at all the schools within the constituency of Barrow and Furness, Mr Woodcock writes: “The man who attacked the Houses of Parliament this week was aiming at a building that symbolises the democratic freedom which is central to our country and way of life.

“I am loathe to give undue prominence to the attack itself or whatever was the twisted mindset that drove it, but I am writing to you today because I do think we should use the tragedy as an opportunity to focus on the important work that parliament does and the values that underpin it.

“I am always willing to host school visits to Westminster, including tours of the palace and the opportunity for a question and answer session with students. I know many schools regularly bring trips down to London and I hope that a visit to parliament can become a regular part of the itinerary."

Counter-terrorism detectives are attempting to trace any associates of Khalid Masood. It has emerged that three more people have been arrested as part of the inquiry, taking the total to 11.

The middle-aged Muslim convert who killed four people in the outrage before he was shot dead by police was born Adrian Elms and also called himself Adrian Russell Ajao.

Asked about where the 52-year-old had been radicalised, Scotland Yard's head of counter-terrorism Mark Rowley said: "Our investigation focuses on understanding his motivation, preparation and associates.

"While there is no evidence of further threats, you will understand our determination to find out if he either acted totally alone, inspired by terrorist propaganda, or if others have encouraged, supported or directed him."

Investigators are appealing for people with information about the terrorist to come forward.