Image copyright Getty Images Image caption Channel 5 have already confirmed Rachel Johnson will appear in this year's CBB

Celebrity Big Brother launches later - but this year's show is a bit different to normal.

All the contestants will be women. To start with anyway.

Channel 5 says it wanted to mark the 100th anniversary of women over 30 being given the vote.

"We approach each series thinking of ways to make it as entertaining and engaging as possible," Tamsin Dodgson, Celebrity Big Brother's executive editor, told BBC News.

"As the nation prepares to mark [the centenary], we're launching the show with female-only contestants which is a gentle nod to this landmark anniversary."

Big Brother has done this before, when the show was on Channel 4.

The eighth series, which aired in summer 2007, saw 11 female housemates enter Big Brother.

Image copyright Getty Images Image caption Chanelle Hayes starred in Big Brother 2007, which also began with all-female housemates

On day three, they added a single male contestant, and then gradually added more men in the following weeks - one of whom, Brian Belo, went on to win.

The results made for arguably one of the most interesting series in the show's history. Viewers watched as the dynamic and behaviour of all the female contestants changed between when there were no men, then one man, and then several men.

"Putting the women in first and allowing them to settle and take control of the house before the men arrive will create an interesting dynamic," says Tamsin.

"How do the different groups cope with power and what impact does gender really have? Fundamentally though it will be a lot of fun to watch."

Dr Helen Pankhurst, an equality campaigner who is Sylvia's granddaughter and Emmeline's great-granddaughter, welcomed the fact the programme would raise awareness.

"Anything that draws attention to the centenary and allows a discussion and gets that message through to different audiences is a great thing," she told BBC News last month.

Image copyright Getty Images Image caption Girls Aloud singer Sarah Harding won the last series of Celebrity Big Brother

"I'll be really interested to hear what the audience have to say about it all and to hear the whole discussion it will promote."

Asked what her grandmother and great-grandmother would make of the plan, Dr Pankhurst said she thought they would laugh, adding: "I really don't know what they would make of the world we live in."

Most of the contestants for this year's show will be unveiled on Channel 5 on Tuesday evening - although they have already revealed that one will be journalist Rachel Johnson.

The most recent series of Celebrity Big Brother, last August, featured Amelia Lily, Paul Danan, Sandi Bogle from Gogglebox and Girls Aloud's Sarah Harding, the eventual winner.

Discussing this series, Tamsin says: "The men will arrive slightly later and Big Brother provides the perfect lens through which to explore what it is to be a woman - and a man - in 2018.

"Gender feels like the perfect concept to explore within Big Brother. Our celebrities, as you'd expect, come with differing backgrounds, experiences and points of view, so I think you can expect a lively, opinionated but ultimately entertaining series to kick off the New Year."

Image copyright Channel 5 Image caption The new series of CBB begins tonight on Channel 5

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