Episode 7 follows the most recent full decade of the Christmas number one battles: the 2010s.

The decade saw The X Factor continue where it left off in the 2000s, undeterred by the Rage Against the Machine battle of 2009.

Elsewhere, the 2010s saw the return of the charity record, with five of the 10 number ones raising funds and awareness for various causes.

The decade also saw the arrival of streaming in the charts, leading to a huge surge in Christmas favourites every year.

Full Christmas number ones (look away if you don’t want ‘spoilers’!):

• 2010: Matt Cardle – ‘When We Collide’
• 2011: Military Wives – ‘Wherever You Are’
• 2012: The Justice Collective – ‘He Ain’t Heavy He’s My Brother’
• 2013: Sam Bailey – ‘Skyscraper’
• 2014: Ben Haenow – ‘Something I Need’
• 2015: Lewisham & Greenwich NHS Choir – ‘A Bridge Over You’
• 2016: Clean Bandit, Sean Paul and Anne-Marie – ‘Rockabye’
• 2017: Ed Sheeran – ‘Perfect’
• 2018: LadBaby – ‘We Built This City’
• 2019: LadBaby – ‘I Love Sausage Rolls’

Episode 6 travels back to the Christmas number ones of the 2000s, a decade dominated by talent shows and reality TV.

After Girls Aloud took on One True Voice in 2002, Simon Cowell saw gold and took over the festive chart for the second half of the decade with his next show The X Factor.

However, this led to one of the biggest chart shocks of all time, when a certain Facebook campaign took the most unlikely artist to the summit by the end of the decade.

Elsewhere, there was yet another Band Aid, an ’80s piano cover and a kids TV show legend.

Full Christmas number ones (look away if you don’t want ‘spoilers’!):

• 2000: Bob the Builder – ‘Can We Fix It?’
• 2001: Robbie Williams & Nicole Kidman – ‘Somethin’ Stupid’
• 2002: Girls Aloud – ‘Sound of the Underground’
• 2003: Gary Jules & Michael Andrews – ‘Mad World’
• 2004: Band Aid 20 – ‘Do They Know It’s Christmas’
• 2005: Shayne Ward – ‘That’s My Goal’
• 2006: Leona Lewis – ‘A Moment Like This’
• 2007: Leon Jackson – ‘When You Believe’
• 2008: Alexandra Burke – ‘Hallelujah’
• 2009: Rage Against the Machine – ‘Killing in the Name’

Episode 5 is a trip back to the Christmas number ones of the 1990s, the decade of Girl Power and power ballads.

Cliff Richard was still around, we said goodbye to a rock icon, Take That were beaten by a bloke in a rubber suit, and the Spice Girls repeated the Beatles’ record.

Novelty was back in the form of Mr Blobby, Teletubbies and South Park’s Chef.

Plus it was the decade that saw festive favourites by Mariah Carey and East 17. But that was about it. And they were in the same year!

Full Christmas number ones (look away if you don’t want ‘spoilers’!):

• 1990: Cliff Richard – ‘Saviour’s Day’
• 1991: Queen – ‘Bohemian Rhapsody/These Are the Days of Our Lives’
• 1992: Whitney Houston – ‘I Will Always Love You’
• 1993: Mr Blobby – ‘Mr Blobby’
• 1994: East 17 – ‘Stay Another Day’
• 1995: Michael Jackson – ‘Earth Song’
• 1996: Spice Girls – ‘2 Become 1’
• 1997: Spice Girls – ‘Too Much’
• 1998: Spice Girls – ‘Goodbye’
• 1999: Westlife – ‘I Have a Dream/Seasons in the Sun’