Belgravia, the lavish new period drama from Julian Fellowes, arrives on ITV on Sunday. Could this epic 19th century tale of secrets and scandals be the series that finally fills that Downton Abbey shaped hole in our lives? Here’s what we know so far...

East Anglian Daily Times: Tamsin Greig as Anne Trenchard and Alice Eve as Susan Trenchard in Belgravia. Picture: Carnival Films/ Robert Viglasky/ ITVTamsin Greig as Anne Trenchard and Alice Eve as Susan Trenchard in Belgravia. Picture: Carnival Films/ Robert Viglasky/ ITV (Image: Robert Viglasky)

What's the story?

It's billed as a tale of of secrets and scandals amongst the upper echelons of 19th century London society. When the Trenchards accept an invitation to the now legendary ball hosted by the Duchess of Richmond on the eve of the Battle of Waterloo, young lovers Sophia Trenchard and Edmund Bellasis forge an ill-fated legacy that will create scandal for generations to come. Some years later when Sophia's parents, the upwardly mobile Trenchards, move to the fashionable Belgravia, they find themselves rubbing shoulders with the venerated Brockenhursts. The two families share a history, but as long-buried events resurface the truth behind their connection becomes hard to conceal.

Who's in it?

East Anglian Daily Times: Philip Glenister as James Trenchard in Belgravia. Picture: Carnival Films/ Robert Viglasky/ ITVPhilip Glenister as James Trenchard in Belgravia. Picture: Carnival Films/ Robert Viglasky/ ITV (Image: Robert Viglasky)

Some of the country's top acting talent - it really is a star-studded cast. Tamsin Greig (Episodes, Green Wing, Friday Night Dinner) plays Anne Trenchard. Born the daughter of a country teacher, she loves her husband, James, and enjoys his success without sharing his social ambitions.

He is played by Philip Glenister (Life on Mars, Ashes to Ashes). A self made man who started out as a London market trader, James grasped the opportunity that war with Napoleon presented, becoming one of the principal suppliers to the Duke of Wellington. After the war, he has joined the Cubitt brothers in their building of Belgravia. Other Trenchard family members include son Oliver (Richard Goulding, soon to be seen in series four of The Crown), his wife Susan (Alice Eve, Star Trek: Into Darkness, Criminal and Bombshell), and sister Sophia (Emily Reid, Curfew). Dame Harriet Walter (Rocketman, The Crown and soon to be seen in Killing Eve) plays Lady Brockenhurst and Tom Wilkinson (The Full Monty, Shakespeare in Love, John Adams) plays the Earl of Brockenhurst, a typical aristocrat who has lived his life according to an accepted code. He loves his wife, even if their marriage is a courteous but essentially external affair of form and rule, manner and custom.

The cast also includes James Fleet (Four Weddings and a Funeral, The Vicar of Dibley, Patrick Melrose), Tara Fitzgerald, (Waking the Dead, Game of Thrones) Paul Ritter (Friday Night Dinner, Chernobyl, Catherine the Great), Diana Hardcastle (Best Exotic Marigold Hotel) and Saskia Reeves (Wolf Hall, Luther, Wallander).

What else do we know?

It's written by Julian Fellowes, adapted from his novel of the same name, and reunites the creative team behind Downton Abbey. Fellowes says that he had long been interested in the Duchess of Richmond's ball, particularly since he adpated Vanity Fair. He says: 'The ball was an extraordinary acme for a certain kind of tragic privilege. Uniquely entitled young men with their nice fiancees, wives and sisters were dancing at the Duchess's ball. Then they left the dancefloor to go straight to the battlefield. Many of the details fascinated me. As the men left and the women were weeping, some people carried on dancing. Some of the young officers were still in their dress coats when they died at Waterloo two days later.

'Belgravia is about two very different women, played marvellously by Tamsin Greig and Harriet Walter. I thought 'what can they have in common? How can I make it believable that they have a relationship?' and it occurred to me that if they have a joint grandchild, that would make for a relationship they couldn't escape from. The story is based on secrets. The audience needs to be constantly surprised. If there are no surprises, then a drama lacks energy.'

Does it have any similarities to Downton Abbey?

'People are entitled to compare the two,' says Fellowes. 'They're not very similar. They are set in very different periods for a start, but they have some elements in common. For instance, if you were a strong and ambitious woman in 1840 or 1912, you had to find different routes around the rules. You had to be creative if you wanted to stay inside society while achieving what you wanted.'

How many episodes are there?

There are six hour-long episodes.

When is it on?

Belgravia starts this Sunday, March 15, at 9pm and will also be streaming on ITV Player.