One of the key architects of Britain’s welfare state would have added loneliness as society’s sixth “giant evil” if he were alive today, Rachel Reeves will say after completing a year-long study into the issue.

The Labour MP, who co-chaired the Jo Cox Commission on Loneliness after her friend and colleague was murdered last year, will argue that the weakening of trade union, church, local pub and workplace ties have left a disconnected society.

“When the culture and the communities that once connected us to one another disappear, we can be left feeling abandoned and cut off from society,” she will say, describing the issue as a new social epidemic.

“In the last few decades, loneliness has escalated from personal misfortune into a social epidemic. More and more of us live alone. We work at home more. We spend a greater part of our day alone than we did 10 years ago. It sometimes feels like our best friend is the smartphone.”

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In a speech at the Policy Exchange thinktank in London to mark the end of the commission, Reeves will say the “crisis of loneliness” would have made William Beveridge revise his list of “want, disease, squalor, ignorance and idleness” to adapt it to the 21st century. She will call for loneliness to be added to the list of immediate and urgent challenges to be overcome.

The MP, who worked with the Conservative Seema Kennedy to continue the commission after Cox was killed, will suggest the issue exposes weaknesses in the welfare state – with top down, target-driven payment by results failing to support people.

“We need a new kind of welfare system that acts as a convenor, bringing people together to help them help themselves,” she will say.

Cox was passionate about the issue, describing loneliness as a “shocking crisis” that she wanted to highlight during her time in parliament.

Reeves and Kennedy have also published a pamphlet in which they warn loneliness is damaging people’s physical and mental health and is more harmful than obesity or smoking 15 cigarettes a day. They also say it inflicts a £32bn cost on the British economy every year.

Prof Jane Cummings, the chief nursing officer for England, said: “I welcome the Jo Cox Foundation’s work to raise awareness of and take action to alleviate loneliness. Social isolation can have a devastating impact not only on people’s mental wellbeing, but evidence shows that it can also increase the risk of premature death by around a third.”

Reeves will claim that teachers, social workers, probation officers and others who can help connect people have been turned into “cogs in a machine”, focused on “meetings, testing, assessing, referring, auditing”.

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“They are good people who want to make a difference, but nothing changes. Beveridge would not only recognise the evil of loneliness, he would follow up on his belief in voluntary action and give more power and control to people,” she will say.

Reeves will suggest that state intervention is not enough, and instead call for a plethora of smaller changes that can help bring people together.