Pearl Mackie has said she wept when she saw her final episode of Doctor Who.

The actor will make her last appearance as the Time Lord’s companion, Bill Potts, in the Christmas special when she bows out alongside Peter Capaldi’s Doctor and show-runner Steven Moffat.

She told BBC Breakfast: “I spent so long saying to people: ‘Oh just be prepared. It’s quite an emotional episode. It’s Peter’s last episode, my last episode. Bring some tissues,’ and I was watching it at the screening and I didn’t bring any tissues.”

Capaldi will be replaced by Jodie Whittaker as the first female Doctor, while Bradley Walsh, Mandip Gill and Tosin Cole will join as new cast members.

Mackie said the role had changed her life, telling the programme: “I don’t really know what I thought it would do, but it’s definitely an epic step-up in career stakes.

“Things that I’m being offered now are very different to things I was getting offered before, which is always positive, and I’m joining the alumni of amazing Doctor Who companions and Doctors that are doing some incredible work.”

The actor said she was now looking forward to watching the programme as a fan, saying: “I’m really excited to watch Doctor Who without knowing what is going to happen. I think that is going to be so cool and it sounds like they are going to be a great team.

“Bradley is really excited about it and I think Jodie is amazing.

“I think it’s going to be great and I’m really excited to watch it as a fan rather than analysing my own performance.”

Doctor Who is on BBC1 on Christmas Day at 5.30pm.