DOMINIC Cummings has appeared to join the Free Britney movement as she tries to force the termination of her conservatorship that has kept her under the control of her father for more than a decade.

Boris Johnson's former top adviser joined the debate in the form of a tweet suggesting people write to the staff of judges in the case, the governor of California, all members of Congress and the president to ask whether they “personally” support the laws allowing Spears to be kept under conservatorship.

He said: "Now @britneyspears can hire own lawyers: please Britney team write/tweet to all in Congress, all @POTUS staff, all @GavinNewsom staff, judges’ staff challenging whether *they personally* support the *shocking* conservatorship laws. They won't & the tide will #FreeBritney"

Spears made headlines around the world last month when delivering explosive courtroom testimony and followed it up last week with more bombshell claims of abuse.

The 39-year-old, whose life and career have been controlled by a complex legal arrangement since 2008, criticised her father and sister on social media.

She wrote to her more than 32 million followers: “So I said ‘life goes on’ in one of my recent posts but it’s always easier said than done !!!!!

“In that moment that’s what felt was the easiest to say but I think we all know that I will never be able to let go and fully move on until I’ve said all I needed to say … and I’m not even close !!!!

“I was told to stay quiet about things for so long and I finally feel like I’m just getting here.”

READ MORE: Dominic Cummings describes Tories winning 2019 election as a 'heist'

Court documents revealed the pop icon described her father Jamie Spears as “threatening and scary.”

A judge last week granted Spears the right to choose her lawyer, allowing her a say in her own legal representation for the first time since 2008. She was deemed unable to look after herself 13 years ago following a series of mental breakdowns.

The 39-year-old star chose Hollywood attorney Matthew Rosengart, a partner at the law firm Greenberg Traurig who has represented several big names including Steven Spielberg and Keanu Reeves.

It was not immediately clear what prompted Cummings to take an interest Spears’s case.