Producers have boosted the cast after Mark Wright, Kirk Norcross, Harry Derbidge and Maria Fowler all left the ITV2 programme following the conclusion of its third run last year.
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Among the new faces are a family of six and property developer Georgia Dorsett, who is tipped to become one of TOWIE's main characters.
Nanny Brighton, grandmother of current cast member James 'Arg' Argent, will also be given a more prominent role after her guest appearance in the 2011 Christmas special.
"Producers have always said they want to keep the show fresh," an insider told The Sun. "That means bringing in new characters and looking at established cast [members] who have new directions in their lives. These new cast members will really shake the show up and give it a new edge.
"Georgina really impressed producers and will become one of the main characters in the new series. She is like a female Mark Wright. Girls really like her and she is a tough old cookie who doesn't take any nonsense."
The source also suggested that there could be further firings on The Only Way Is Essex, saying: "The current cast can't be complacent and have to up their game to compete with [the newcomers]. Nobody's place in the show is guaranteed."
The Only Way Is Essex producers are due to confirm the full line-up for series four of the show later this week.
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