The woman behind the Supreme Court case that forced Theresa May to get parliamentary approval for triggering Article 50 is planning to “build the biggest tactical voting effort in UK history” to support election candidates opposed to hard Brexit.

Gina Miller said the group called Best for Britain will aim to back parliamentary candidates from all parties “who campaign for a real final vote on Brexit, including rejecting any deal that leaves Britain worse off.”

A Crowdfunding page set up after Theresa May called the 8 June election has already raised more than £70,000 of the £80,000 required for the campaign..

“We want to build the biggest tactical voting effort in UK history to ensure that candidates across the country that promise to do what’s best for Britain in the Brexit process get the extra support they need to win,” Ms Miller told The Guardian.

The investment manager added: “If the deal the next government negotiates doesn’t match up to our current terms, MPs should do what’s best for Britain and reject it. We will be asking MPs to pledge to keep an open mind and not be bullied into giving the next government a blank cheque for the final deal.”

Best for Britain, which will formally launch next week, has already appointed the executive director of global policy for anti-poverty organisation the ONE Campaign, Eloise Todd, as its campaign director.

How Brexit affected Britain's favourite foods from Weetabix to Marmite Show all 8 1 /8 How Brexit affected Britain's favourite foods from Weetabix to Marmite How Brexit affected Britain's favourite foods from Weetabix to Marmite Weetabix Chief executive of Weetabix Giles Turrell has warned that the price of one of the nation’s favourite breakfast are likely to go up this year by low-single digits in percentage terms. Reuters How Brexit affected Britain's favourite foods from Weetabix to Marmite Nescafé The cost of a 100g jar of Nescafé Original at Sainsbury’s has gone up 40p from £2.75 to £3.15 – a 14 per cent rise—since the Brexit vote. PA How Brexit affected Britain's favourite foods from Weetabix to Marmite Freddo When contacted by The Independent this month, a Mondelez spokesperson declined to discuss specific brands but confirmed that there would be "selective" price increases across its range despite the American multi-national confectionery giant reporting profits of $548m (£450m) in its last three-month financial period. Mondelez, which bought Cadbury in 2010, said rising commodity costs combined with the slump in the value of the pound had made its products more expensive to make. Cadbury How Brexit affected Britain's favourite foods from Weetabix to Marmite Mr Kipling cakes Premier Foods, the maker of Mr Kipling and Bisto gravy, said that it was considering price rises on a case-by-case basis Reuters How Brexit affected Britain's favourite foods from Weetabix to Marmite Walkers Crisps Walkers, owned by US giant PepsiCo, said "the weakened value of the pound" is affecting the import cost of some of its materials. A Walkers spokesman told the Press Association that a 32g standard bag was set to increase from 50p to 55p, and the larger grab bag from 75p to 80p. Getty How Brexit affected Britain's favourite foods from Weetabix to Marmite Marmite Tesco removed Marmite and other Unilever household brand from its website last October, after the manufacturer tried to raise its prices by about 10 per cent owing to sterling’s slump. Tesco and Unilever resolved their argument, but the price of Marmite has increased in UK supermarkets with the grocer reporting a 250g jar of Marmite will now cost Morrisons’ customers £2.64 - an increase of 12.5 per cent. Rex How Brexit affected Britain's favourite foods from Weetabix to Marmite Toblerone Toblerone came under fire in November after it increased the space between the distinctive triangles of its bars. Mondelez International, the company which makes the product, said the change was made due to price rises in recent months. Pixabay How Brexit affected Britain's favourite foods from Weetabix to Marmite Maltesers Maltesers, billed as the “lighter way to enjoy chocolate”, have also shrunk in size. Mars, which owns the brand, has reduced its pouch weight by 15 per cent. Mars said rising costs mean it had to make the unenviable decision between increasing its prices or reducing the weight of its Malteser packs. iStockphoto

On its Crowdfunding site, it says it will “support parliamentary candidates who commit to keeping the options open for the British people” and “fight to make the Brexit deal process transparent, honest and democratic.”

It also promises to “tour marginal seats to make sure the next Government has no mandate to destroy our rights and our relationship with Europe.”

Ms Miller said the hadn’t been time to organise “a formal progressive alliance,” so “we have to do what we can in the time available. We need to re-energise people about the importance of voting tactically.”

After defeating the government at the Supreme Court Ms Miller was subjected to barrage of abuse, along with her fellow claimants.