The romcom, which features Thompson finding a necklace that her husband has bought for another woman and breaking down in floods of tears when she realises she has been cheated on, is a festive favourite for its Christmas setting.
Now, an interview with Thompson at a 2018 fundraiser has shown that she drew on her real-life experience of heartache after ex-husband Kenneth Branagh, who she was married to from 1989 to 1995, allegedly cheated on her with Helena Bonham Carter.
In the old interview, Thompson says of the film: "That scene where my character is standing by the bed crying is so well known because it’s something everyone’s been through.
"I had my heart very badly broken by Ken. So I knew what it was like to find the necklace that wasn’t meant for me.
"Well it wasn’t exactly that, but we’ve all been through it."
Thompson has been happily married to actor Greg Wise since 2003, who she shares two children with, and she recently supported him from the audience as he competed in Strictly Come Dancing.
Back in 2012, Thompson had told The Times that she had long since forgiven both Branagh and Bonham Carter.
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She said: “I’ve had so much bloody practice at crying in a bedroom, then having to go out and be cheerful, gathering up the pieces of my heart and putting them in a drawer.
“That is... all blood under the bridge. You can’t hold on to anything like that. I just think... pfft.
“It’s pointless. I haven’t got the energy for it.. Helena and I made our peace years and years ago... she’s a wonderful woman.”
Thompson recently hit headlines for her enthusiastic dancing to Adele's break-up anthem Rolling In The Deep at ITV's An Audience with Adele.
Watch: Emma Thompson dances at An Audience with Adele