Of the 20 shadow cabinet ministers who stepped down after the EU referendum, 15 are still doing work related to their former briefs, including interventions in Commons debates and media appearances.

The "shadow shadow ministers", as they have been nicknamed, are however afraid that working this way isn't sustainable, and think Jeremy Corbyn needs to come up with a better way of bringing Labour together if he is re-elected as leader later this month.

"Housing is an area where I have a deep passion, and a growing concern about the housing crisis," former minister John Healey told BuzzFeed News.

"But specifically, having stepped down from the shadow cabinet in the summer, there was no way that I was going to allow a government that has had a track record of six years of failure on every front of housing not to be held to account for want of someone in the shadow cabinet or on the front bench able to do that."

Since leaving the shadow cabinet, Healey has spoken in the chamber against cuts to housing benefits for social housing and to point out that fewer houses were built under David Cameron than under any other prime minister since the 1920s.

He is also still working on several reports which will be published later this year. His position as shadow housing and planning minister has not been filled in Corbyn's shadow cabinet since he quit.

Kerry McCarthy, the former shadow environment secretary, is also keeping up work on her brief out of a sense of duty.

The Department for Environment, Food & Rural Affairs "has a lot of stakeholders, particularly on animal welfare ... they're quite disappointed with the government and looking to Labour," she said. "We can't make people feel like there's a vacuum.

"On things like the badger cull, it's amazing how people seem to have to be told over and over again what Labour's position is; people even started to say to me, 'Has Labour changed position?', because Jeremy hasn't said anything about it. You keep having to get it out there."

This is why she has given interviews to relevant trade magazines, including "waste resources journals", and participated on debates in the Commons about the risks posed to animals by snares, the consequences of Brexit on environment-related issues, and other issues.

She is worried that her successor, Rachael Maskell, won't be able to do the job alone: "I sat down with Rachel and talked about the portfolio and she's trying to get her head around it, but she's one person, when I used to have a team of two shadow ministers and Maggie Jones in the Lords: She's going to struggle to keep up.

"In terms of legislation, there is going to need to be a concerted effort: If there was a DEFRA bill going through, I'd be quite keen to make sure that Rachael doesn't struggle along by herself. She's very capable but one person alone can't do it."

This sentiment was echoed by Lucy Powell, formerly shadow education secretary. She gave several interviews on grammar schools last week, knowing her replacement, Angela Rayner, had to be in the chamber after tabling some urgent questions.

"Education policy has long been a personal passion and commitment of mine so my intention was always to carry on campaign on those issues," Powell said, "but it's certainly not my intention for that to look like any kind of reflection on my successor."