Helena Bonham Carter says being invited to a royal sleepover is a ''thrill''.

The 53-year-old actress - who plays Princess Margaret in season three of 'The Crown' - is one of a select group of people who have been invited to a royal sleepover at Windsor Castle, and it's an experience she relished.

She shared: ''They actually call them sleepovers.

''I think The Queen has about 10 of them a year so she can meet certain people, and I have to say, when I stayed over, it was a really odd group.

''It was about six years ago when I was still with Tim [Burton, her director ex-husband]. Daniel Craig was there with Rachel [Weisz, his wife], and there were other people in the arts as well, and also, the Brazilian Ambassador.

''I stayed in the Prince Charles Suite. It was a thrill and you really felt like you were in 'The Crown'. And I remember there was a lady standing by the door, and she just carried on standing there.

''And we went to the toilet, came back, and all our bags had been unpacked automatically. I said to her, 'Are you all right?' and she said, 'I'll just be remaining here. Do you want your bath to be drawn? Will you be wanting tea in the morning?' It was amazing. It was really surreal.''

Asked about her interactions with the Queen, the acclaimed actress told news.com.au: ''Well, the Queen was in full regalia and she was wearing a tiara.

''We all had to dress up [for dinner] and I sat next to the Duke of Edinburgh, who was very mischievous.

''He took us on a full tour of Windsor. They have an amazing library there which is basically the history of England. And what I liked about them was that there was a feeling that they feel they're just borrowers, that they didn't see it as their property.''