The people sitting beside us had dressed up and the glass of champagne they were drinking was probably not their first that day. Clearly, they had come to celebrate a reunion with old friends.
Which is how it felt. We know most of the characters.
Lady Mary (Michelle Dockery) and Tom (Allan Leech), Robert (Hugh Bonneville) and Cora (Elizabeth McGovern), Edith (Laura Carmichael) and Bertie (Harry Hadden-Paton) are 'family" upstairs.
Violet (Dame Maggie Smith) and Isobel (Dame Penelope Wilton) are still sparring – with one-liners and put-downs which are even better than I remember them, and are greeted with appreciate chuckles and sporadic bursts of applause from the audience. And we have a worthy addition to the badinage – the former Dolores Umbridge (Imelda Stanton) - whose plans stand in the way of Violet's ambitions. May battle commence.
Downstairs, just about everyone – even including the retired Mr Carson (Jim Carter) is there. And all of them are awestruck by the impending visit of King George V and Queen Mary.
The big screen, and a movie budget allow everything to be even more lavish than usual.
Add a power struggle between the Royal Staff and the Downtown regulars, a mysterious and sinister stranger, a foiled assassination attempt, a light-fingered staff member, the arrest of a homosexual staff member for the crime of being gay and a plot where women by and large are front and centre and the men play supporting roles and you get the picture.
Does it add a great deal to the Downtown story? Probably not.
But it lets us escape into a somewhat idealised nostalgia, and feels like a visit to old friends.
Some of the reviews talk about this as the "last hurrah" of the series – and that may be true.
But if, a year or so from now, there were to be a sequel would I go?
And the applause at the end of the movie(and not only from our champagne drinking companions) suggests that I would not be on my own.