The man suspected of murdering Sir David Amess tricked the MP’s constituency office into giving him an appointment by falsely claiming he wanted to discuss healthcare, it has been claimed.
Ali Harbi Ali, 25, who is in police custody, allegedly lied to staff by also claiming he was moving to the area.
Mr Ali, who lived in Kentish Town, in North London, travelled to Leigh-on-Sea by train to carry out what is now being seen as a deliberate attack on the British state.
Security services and counter-terroism police are trawling through Mr Ali’s phone, computer and contacts, but do not currently believe the killing was part of a wider plot.
Watch: Sir David Amess - UK's parliament pays tribute to murdered MP
Unlike other high-profile Islamist attacks in recent years, only Sir David was targeted. In attacks in London, for example, jihadists have gone on the rampage, killing indiscriminately before in many cases being shot dead by police as part of a martyrdom ritual.
But in this case, it is claimed that Mr Ali calmly used his mobile phone - to either make a call or send text messages - before waiting to be arrested.
“There will be a lot of concern as to whether this incident is part of a wider messaging,” said one security source.
On Monday night, CCTV footage of the suspect walking in North London on the morning of the attack emerged.
The footage, obtained by Sky News, shows Mr Ali dressed in a green parka jacket, carrying a backpack over his right shoulder.
Appointment reportedly made a week earlier
Sources have told The Telegraph that Sir David was “unlucky” and that Mr Ali had decided to kill an MP before selecting his target.
Sir David, 69, a father-of-five, advertised his constituency surgeries on Twitter, including the one held last Friday at Belfairs Methodist Church in Leigh-on-Sea. It is unclear if Mr Ali made the booking before or after the location of the surgery was posted on social media.
One source said on Monday: "A week before the murder, Mr Ali contacted Sir David's constituency office to make an appointment to see him during his Friday surgery.
“Although the sessions are reserved for constituents, it is understood he told staff he was moving into the area imminently and had a number of issues relating to healthcare that he wished to discuss."
Debate continues over MPs' security
Priti Patel, the Home Secretary, and Lindsay Hoyle, the Speaker of the House of Commons, met on Monday to discuss whether to change the security arrangements for MPs.
In the immediate aftermath of Sir David’s death, all MPs were urged to meet with their local police forces to discuss whether to tighten security.
Decisions about how to ensure the safety of constituency meetings are traditionally taken by individual MPs and local police officers together, rather than imposed from above.
However, there has been discussion about whether to update and expand the guidance and protections offered to all MPs by the Parliamentary authorities.
Suspect remembered as 'friendly and polite boy' in his youth
Details began to emerge last night of Mr Ali’s upbringing in Croydon, in South London, adding mystery to why he allegedly carried out the attack.
Mr Ali had been reported to Prevent, the Government's counter-extremism strategy, but remained under the radar and his name was never flagged to MI5. The domestic intelligence agency has a file of 40,000 terror suspects, including 3,000 jihadists being actively investigated at any one time.
Sources said Mr Ali had no previous criminal record and no reported mental health issues either.
Despite coming from a Muslim family, Mr Ali, the eldest of four siblings, attended the Church of England’s Parish Church Infant and Junior School in Croydon, where he was remembered by staff as a "friendly and polite boy".
He was a keen chess player and, like his siblings, took part in the school's traditional Christian traditions.
Watch: Police review CCTV in Amess investigation
One teacher, who did not wish to be identified, said: "Ali wasn't a high flier, but was a hard working child who was especially good at maths.
"When I realised who had been arrested I thought: ‘What a waste.’ It unsettled me. As teachers, we try to sow seeds that will grow, but not all of them do.
"The point of education is to help development and if something goes wrong, it is so hard to fathom why."
At the age of 11, Mr Ali moved to Riddlesdown High school in Purley, where the supermodel Kate Moss was once a pupil.
He stayed on at the school's sixth form, where he completed A-levels before leaving in order to go to university. It is not clear if he took up any place offered.
Gordon Smith, chief executive of Riddlesdown, said the school had been working with police since the weekend and had been left "devastated" by events.
Neighbours in Croydon said Mr Ali had left home around 2014, but remained a regular visitor to his mother’s house.
His parents split when he was still at primary school and his father spent much of his time in his native Somalia.
A woman who lived next door said: "They're a really nice family but we haven't seen them for a long time. We saw the police pull up on Friday, I did ask them [what was happening] but they wouldn't say.
"I knew Ali when he was young but then he went to college or uni we haven't seen him for a long time.
"Every day I'd see her [the mum] go shopping and she'd always say hi. I'm really saddened for her because she's really nice.
"I feel we actually know them so it was quite a shock. We haven't seen [Ali] for many years to be honest. As far as I know he went to university.
"All the children were hard working students. We used to see Ali out playing football as a kid. It's quite a shock, it’s a shame really I feel more sorry for the mother to be honest."
Police were continuing to question the suspect on Monday night. They currently have until Friday to charge him.
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