The battle lines were drawn instantly within the Cabinet along the "Leave" or "Remain" campaign, with Priti Patel, the senior-most Indian-origin member of the Cabinet, coming out openly in favour of leaving the EU.
Ahead of the Prime Minister's address to the parliament on the proposed EU deal struck in Brussels, the UK employment minister and Cameron's Indian Diaspora Champion joined other senior colleagues like UK justice secretary Michael Gove and Northern Ireland secretary Theresa Villiers.
"For too long the EU's unaccountable institutions have meddled in our affairs, imposed unwelcome and costly laws on this country, prevented us from deporting those individuals who should not be in this country and they have taken money from hardworking taxpayers' pockets.
Each week 350 million pounds of taxpayers' money is sent to Brussels and this would be better spent in this country on our own priorities," she said.
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In his interview with the newspaper, Cameron in turn challenged these Eurosceptics to explain to the British public what the country's relationship would be like with Europe if the UK voted to leave.
"Most trade deals take four, five, six years to negotiate and so the people who want to support that have got to set out what it means. If you have a deal like Norway you pay as much in per head but you have no say over the rules and you are subject to free movement."
Asked by the BBC if he would like to send Johnson a message, Cameron said: "I would say to Boris what I say to everybody else. We will be safer, we'll be stronger, we'll be better off inside the EU.