Rachel Thomas, with her children, Pita Roberts, 9, left, Jai Roberts, 5, and Tema Roberts, 11. They will be walking to Wellington to protest the TPPA.

Christchurch woman Rachel Thomas and her three children will walk from Christchurch to Wellington to protest the proposed Trans Pacific Partnership Agreement (TPPA) trade deal.

Thomas and her children, Tema​,11, Pita, 9, and Jai, 5, will set off at 9.30am from Cathedral Square and make their way to Kaiapoi with about 40 supporters.

The walk will take three weeks with the group expected to arrive in Wellington on November 3.

Speaking from the house bus she shares with her children and partner, Justin Roberts,Thomas said the trade deal, which was signed by the Government in February, could still be over-turned.

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"For a while there was a lack of momentum . . . and it appeared it had been signed and there was nothing we could do about it. But I know it isn't over and we can make a change. I want this action to be a reminder to people it still exists and we can still do something about it."

The former social worker believes the TPP will give corporations too much power and limit the Government's ability to protect the environment and vulnerable people.

Her children, who she home-schools, were a big part of her motivation to set off on the walk.

"I'm just really passionate about my children's future and what they are going to have when they are my age and I really hope that this hikoi is something that can build on their experience and give them confidence that they can do anything," Thomas said.

Tema said she did not take her mother seriously when she first proposed the walk and thought she had "gone crazy".

Since then, she had got on board with the idea and thought it was "pretty cool" .

Thomas said she and the "It's Our Future" group had prepared for all contingencies for the three-week walk and liaised with police on safety measures.

Two vans would support the walkers and Thomas said the children would take a break in one of the vans if they got too tired. She was taking a push-chair for Jai.

The family had been offered accommodation at different points and food sponsorship from local companies.

When they arrived in Wellington, they would go to parliament and ask opposition politicians to "be in true opposition and pledge to reject the TPP".

Thomas was inspired to embark on the march through her involvement with anti-TPP group It's Our Future, which she joined three years ago.

"You reach a point when the evidence builds up overwhelmingly and you cry out to everyone, 'someone's got to do something about all this', and then it hits you – that someone is me."