Dame Emma Thompson decorated Alan Rickman's hospital room prior to his death so he would feel more at home

She told The Sunday Times newspaper: "I think he wanted to say goodbye to his friends and have it under his control. He even organised his own funeral because he didn't want it to be a mess."

Horton revealed one of Rickman's regular visitors was his longtime pal Dame Emma Thompson, who brought in throws and a standing lamp to help make the actor feel comfortable.

Horton explained: "[Thompson was] creating a salon around him while he was in bed. She brought in a standing lamp and throws so that it didn't feel like a hospital room."

She went on to explain Rickman had one request from his doctors, saying: "The first thing he ever said to the oncologist was: 'I don't want to die in pain' and they made sure he didn't".

The pair decided to keep the actor's cancer secret because he didn't want anyone to feel sorry for him and Horton admits she tried not to do any online research about the disease.

She said: "We didn't tell anybody apart from our families at first. Alan didn't want people to look at him and say: 'Oh, how sad' ...

"We knew it [the cancer] was fully grown and had spread. I didn't Google it or anything, I didn't want to know, but we knew what it meant.

"We knew the chemo wouldn't work, but you live in hope. You say, maybe we'll be the exception where it does."

Horton previously opened up about how Rickman planned his own funeral and chose Bruno Mars and Mark Ronson's hit track Uptown Funk to be played for mourners.

In an extract from the book Madly, Deeply: The Alan Rickman Diaries, Horton explained: "He designed his own funeral. Ian Rickson (theatre director) was put in charge.

"Alan chose where it would take place, who would speak and what music would be played. He was surrounded by people who loved him and up until 13 January was still in control of everything that was going on around him.

"But he wasn't there after that, and he died at 9.15 in the morning of 14 January 2016. I was there. He wasn't in pain. He just went.

"Alan was cremated on the morning of 3 February with close friends and family present. The funeral service was held that afternoon in the Actors' Church in the heart of London's theatre district.

"The chosen music was Uptown Funk and Take It with Me by Tom Waits. We finished with everyone singing The Sun Ain't Gonna Shine Anymore.

"Then, in keeping with tradition, the Reverend Richard Syms asked us to give Alan 'one last wonderful standing ovation'."