Matt Smith is planning a festive proposal

A source told Grazia magazine: "They are absolutely besotted and a wedding has been on the cards for a while.

"The question has always been finding a time when they're not both up against it with work. They've openly discussed getting married in the past."

Matt, 34, reportedly decided to wait to propose until the "fuss" surrounding his Netflix miniseries 'The Crown' - in which he plays Britain's Prince Philip - had died down.

Another source said: "Now that the series has aired, he's focusing on his love life."

Lily, 27, recently admitted she enjoys going out and dancing on tables with the former 'Doctor Who' star.

She said: "I love dancing but I don't do it very much now unless I'm drunk. Me and Matt have been known to dance on a table."

And the couple - who starred together in 'Pride and Prejudice and Zombies' - also enjoy their time when they're not out getting drunk as they moved in together earlier this year.

A source said previously: "They are head over heels and both think they have found the one. Lily moved into Matt's London home and there's been no arguing over who's hogging the bathroom cupboards - yet."

The 'Cinderella' star previously admitted she admires her boyfriend's sense of style so much, she likes to ask him to help choose her own outfits.

She said: "He's got great taste so I run things by him. He's got a good fashion eye."