The well-established actress explained the cast of Downton were aware of Julian Fellowes’ plans to end the drama after series six as they filmed series five, last year.

She said: “Everyone knew in series five that series six was going to be the final series, and knowing the little I know about the direction it’s going in it totally makes sense.

“I think it will come to a very exciting and fulfilling conclusion. Julian’s sort of thought long and hard about it and it’s the best possible ending.”

With such a huge cast and crew, it seems surprising the news was kept between them without one slip up. Did Catherine find the secret hard to keep?

“No, it wasn’t difficult to keep the secret because everybody just does. I suppose it’s the same as any series that people are interested in.

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