He died on Friday after being stabbed multiple times during meetings with constituents.
Boris Johnson announced on Monday that Southend will be given city status in tribute to Sir David Amess, killed last week while meeting constituents.
Amess, 69, was killed on Friday. He had been an MP for 40 years and it was a running joke for his colleagues that not one of his allocutions in parliament didn't include a plea for Southend, in the southeastern county of Essex, to be given city status.
The Prime Minister confirmed on Monday during a special session in parliament to honour the slain Conservative lawmaker that "Her Majesty has agreed that Southend will be accorded the city status it so clearly deserves".
"The last 72 hours has done little to numb the shock and sadness we all felt when we heard of the tragic and senseless death of Sir David Amess," Johnson also said.
"Nothing I or anyone else can say will lessen the pain, the grief, the anger they must feel at this darkest of times."
“Sir David was taken from us in a contemptible act of violence striking at the core of what it is to be a member of this House, and violating both the sanctity of the church in which he was killed and the constituency surgery that is so essential to our representative democracy.”
The Prime Minister's allocution at times drew laughs from the House, recalling Sir Amess' boundless pride in his constituency and his pleasure to serve the British people whether it was while campaigning for Brexit and more freedom for the people of Iran or taking part in the Westminster Dog of the Year contest and the annual parliamentary pancake race.
He also reiterated that Amess had been "one of the kindest, nicest, most gentle" people in politics.
A 25-year-old British man, Ali Harbi Ali, was arrested shortly after the stabbing was reported on Friday and is being held on suspicion of murder. Police say the suspect appears to have acted alone and may have had a “motivation linked to Islamist extremism”.
Many MPs also paid tributes to their slain colleague, painting the picture of a hard-working, gentle and generous man.
Monday's session in the House of Commons follows a three-week break and most of the scheduled business has been replaced by tributes to Sir David. That will be followed by a service at the medieval St. Margaret’s Church in the shadow of Parliament.
The leader of the main opposition Labour party, Sir Keir Starmer, told his fellow lawmakers on Monday that "we must not lose sight that David’s killing was an act of terror in our country."
"A cowardly attack on a public servant doing his job is an attack on our country and our way of life."
He also praised Amess for putting "people before his party" and "own patch before his personal advancement".
He described him as a political opponent, adding: "I use that phrase political opponent very deliberately, because David held his beliefs very passionately but gently.
"And I believe that not only can we learn from that, but we have a duty to learn from that," he said.
The government has ordered a review of MPs’ security following the attack on Friday. British politicians are protected by armed police when they are in parliament but generally are not given such protection when they meet with constituents in the districts they represent.
Many politicians say the amount of abuse they receive, both online and in-person, has soared in recent years.
Police in Wales said Monday they had arrested a 76-year-old man on suspicion of sending a death threat to Labour MP Chris Bryant, the latest in a string of threats to politicians.
Police have until Friday to question the suspect, and are working to determine what, if any, connection he had to Sir David and why he targeted the MP. The politician's meeting with voters in the seaside town of Leigh-on-Sea was public and open to all.
Sir David’s family said in a statement that they were struggling to comprehend what had happened.
“We ask people to set aside their differences and show kindness and love to all,” said the politician’s wife and five children. “This is the only way forward. Set aside hatred and work towards togetherness.”