Downton Abbey (Peacock/PBS)

Downton Abbey returns! Delight for fans as filming secretly starts on a new series of the show in surprise comeback               

Filming has secretly started on a new series of Downton Abbey.

The period drama – the last episode of which was aired a little over eight years ago – is making a surprise comeback in a seventh series.

Bosses hoped to be able to bring back some of the big name actors such as Hugh Bonneville, Michelle Dockery, Elizabeth McGovern and Joanne Froggatt who appeared in the previous six seasons and two movie spin-offs.

While it is not known if all of them have signed up, chiefs are said to be 'thrilled' with their casting.

The return of the show, which was filmed at Highclere Castle in Hampshire and which covered the many societal changes and world events between 1912 and 1928, is expected to be on screen at the end of the year.

Old episodes of Downton are well watched on the channel's streaming platform ITVX so TV insiders expect they will do what they can to stop it going to rivals such as Netflix or Amazon.

A source close to the project told the Mail: 'Filming has been going on for a few weeks now, it is all very, very secret. There are people working on it who have never seen secrecy like it.

'Those working on the set have been made to sign non-disclosure agreements so that they don't give the game away but there is a lot of excitement at the return of Downton.

'It was such a huge success before and there are so many more stories to be told, it seemed such a shame not to be able to make more of it but they've made it happen.'

The Mail on Sunday revealed last May that bosses were hoping to revive the series and in December creator Julian Fellowes did not rule out the return when asked if it would make a comeback.

He told Radio Times: 'I have said goodbye to Downton so many times, and I have written the last scene about six or seven times. Now I've got out of the habit of making permanent statements about whether it's gone.

'It just gives me a lot of pleasure that so many people enjoyed it, so to feel that you created a show that cheers people up and they had a good time with it, I love that.'

The final episode of the show – which acted as a launch pad for the careers of Ms Dockery, who played Lady Mary, Lily James, who played Lady Rose, and Jessica Brown Findlay, who played Lady Sybil, was aired on Christmas Day 2015, with the viewing figure peaking at 7.4million.

In the finale, viewers saw Edith – portrayed by Laura Carmichael – and Bertie, played by Harry Hadden-Patton, finally get married, on New Year's Eve 1925.

The final series was followed by two movies, one in 2019 and the other in 2022.