Richard E Grant has expressed his delight at joining the cast of Downton Abbey.

The 56-year-old actor will reunite with Gosford Park writer Julian Fellowes on the British period drama, when he joins the show in its upcoming fifth season.

Speaking to Vulture, Grant joked that he long suspected he would be left out of what he described as the Downton Abbey "phenomenon".

"Of all the Gosford cast, only Dame Maggie Smith was cast in Downton Abbey," he said. "I thought there was kind of, for want of a better term, a creative embargo there. That Julian didn't want any overlap."

The Withnail and I star added: "Journalists over the years have said to me, 'Are you going to be in Downton? Why aren't you in Downton?' I didn't feel like I could email Julian to say, 'Oy! Can you please write me a part?'

"He knows who everyone is. He was an actor. I would imagine if I had done that it might have had the reverse effect. So nothing happened, and I thought, 'Ah well, I've missed out on the Harry Potter franchise, and I'll miss out on the Downton phenomenon'. 

"Then a month ago, I got an email asking if I'd do four episodes, and instead of playing someone downstairs, like I did in Gosford years ago, would I play someone upstairs? I said yes fast. But it's possible someone else turned it down or dropped dead. Who knows?"

Grant - most recently seen in HBO comedy, Girls - was also asked to reveal details about his Downton Abbey character.

"I'm allowed to tell you his name is Simon Bricker and that he is an art historian," he said. "I'm told if I say anything more my knees will be taken off."