Downton Abbey Christmas special trailer released

The cast of 'Downton Abbey'.

It may be cold and wintry outside, but it's summer time in Downton Abbey this Christmas.

The drama returns to ITV on Christmas day for a two hour special which sees the Crawleys relocated to their London residence at the height of the social season.

The new trailer reveals little more about the plot details ITV first released a week ago, but does show an icy exchange between The Dowager Countess and Lady Cora's mother, Martha Levinson.

In the teaser, Martha tells Lady Grantham: "The gang's all here!", to which she replies coldly: "Is that American for hello?"

Later on in the one minute clip, Martha, fresh from New York, warns the Dowager: "My world is coming nearer, and your world is slipping further and further away."

Bates' questionable crime looks like it could come to the fore this Christmas, as the Crawleys become implicated in a scandal that poses a threat to the monarchy.

While Edith struggles to decide whether to keep her baby or not, things are right as rain for Rose, who is presented at Buckingham Palace to the King as part of her 'coming out'.

Lady Mary's two admirers continue to vie for her attention, but this Christmas even grouchy Isobel Crawley could have a smile on her face after she finds an admirer.

Below stairs, Daisy is treated to an unexpected visitor, who Carson thinks has ulterior motives.

Downton favourites Maggie Smith, Hugh Bonneville, Michelle Dockery, Laura Carmichael and Elizabeth McGovern return for the Christmas special.

The actors are joined by American stars Shirley Maclaine, who returns to play Lady Cora's mother, and Sideways actor Paul Giamatti.

* nzherald.co.nz will have a full review of tonight's Downton Abbey finale on Prime at 10pm by TV columnist Chris Philpott, when the episode finishes airing.

- Independent