The Budget that will lift lid on troubled Coalition A fortnight after his Swedish meeting, Mr Clegg had publicly suggested he wanted to increase the tax-free personal allowance more quickly than planned. In interviews with this newspaper, Danny Alexander, the Lib Dem Treasury minister, first set out proposals to cut pension tax relief for higher earners - before, Mr Clegg himself called for the introduction of a "tycoon tax." There were also increasingly public calls for a mansion tax on expensive properties. By the beginning of this month, distrust at the Treasury had become so high that Mr Clegg's aides were being prevented from receiving confidential figures being requested. Last Thursday, as the Prime Minister was settling down for a private dinner with his wife in New York - and Mr Osborne had just arrived back to Britain on a transatlantic flight from Washington - they were presented with a front-page story in the Lib-Dem friendly Guardian newspaper saying the Tories were poised to scrap the 50p rate of tax. "If this story proves true, we really will get them this time," said one senior Conservative away from the negotiations. It now appears that the Government was waiting for the crucial "scorecard" - the independent watchdog's analysis of the budget's proposed measures - before the deal could proceed. But, they effectively got the go-ahead on Friday when the Office for Budget Responsibility signed off the figures. Both parties are now confident that they have their own "political" announcement from the 50p deal. The Tories will be able to tell their supporters that they have got rid of the controversial top rate. The Liberal Democrats will be able to tell theirs that the richest Britons will pay more tax - as the official analysis will show that the closing of loopholes will raise more money. In economic terms, the replacement of the 50p rate may therefore be a "score draw." But, politically, the long-term ramifications of the last few weeks are not yet clear although it has certainly led to bad blood between the Coalition partners. Mr Cameron takes a relatively sanguine view of events as he is keen to help support Mr Clegg, whose poll ratings are terrible, but whose determination to keep the Coalition intact until 2015 is crucial. Aides fear that if the Lib Dem leader is pushed too far, or humiliated in public, his party will quickly turn on him. However, throughout Government, there is now growing mistrust between Conservative and Liberal Democrat ministers. But, away from the high-profile spat between the Coalition partners, this budget has also opened up the first signs of a crack between Mr Osborne and Mr Cameron. Although the two men are still very close - and travelled together to Washington last week - the Prime Minister has demanded the softening of the child benefit policy. He is also thought to be less keen on scrapping the 50p top rate of tax imminently - for fear of being accused of pandering to the wealthy. Further debate will soon start on the Prime Minister's cherished policy of tax breaks for married couples, which the Chancellor is said to be cool on. The quad of senior ministers will meet face-to-face today to finalise the "presentation" of the budget. It is expected to be a relatively brisk and businesslike affair rather than the celebration of a carefully-put together economic document.