Jed Mercurio says Line of Duty season six has "to complete filming by Christmas" to be on air in 2021

"Soon," said executive producer Simon Heath.

Mercurio joined in: "We do [know the date]. It won't come as a surprise to us. There are a few things to figure out, but we're working towards a day... I know a date has been talked about in the press, but as usual they got it wrong."

He added: "We are working towards a day and if we can get over all the hurdles we will be back filming."

Mercurio emphasised season six had to be filmed by Christmas if it was going screen in 2021.

"We'd love to be on air next year, so we really have to make sure we complete our filming before Christmas."

Cast such as Martin Compston (DS Arnott) and Vicky McClure (DC Fleming) joined the producers for the Q&A, which can be viewed on the Radio Times Facebook page.

When asked if Mercurio had been rewriting scripts to accommodate social distancing guidelines, Compston offered: "We'll have to do some rewriting to accommodate the stone of weight I've put on!"

Mercurio thought this this innovation had legs. "Arnott can go undercover and part of his disguise is he's a stone heavier."

He continued: "To be honest, it's a good question about what we're going to do. We're still talking about it. There are some things we can do [to adapt to guidelines], very simple things that the audience won't notice, like have as many scenes outdoors as possible, which allows social distancing of the crew and it's a safer environment for COVID. We're looking at things like that, which are invisible changes, but we'd have to think very carefully about doing visible changes."

Mercurio said there were industry-wide guidelines which Line of Duty producers "take very seriously".

"We're taking the best advice on how we can keep people safe and still be able to work in the way that we want to do."

Questioned about whether core cast such as guest star Kelly Macdonald would be available, he joked: "Yes, because otherwise we're f**ked!"

There was even a suggestion that Lennie James (season one's DCI Gates) could step in if Macdonald was unavailable...

"I'd be really good as Kelly Macdonald," he quipped. "I think I'd be an excellent Kelly Macdonald. I think you should give me a chance!"

Line of Duty season one continues on BBC One on Tuesday night and all five full seasons can be watched on iPlayer.

If you're looking for more to watch, check out our TV guide.