Behind the cautious words publicly uttered by various senior government figures since the start of this week about “progress” and “hope” towards a global tax deal, sources at the heart of talks are clear that the phrase “at least” has been erased from the reference to a 15 per cent minimum corporation tax rate in a new text circulated by OECD officials facilitating the talks ahead of a marathon 140-member videoconference to try and get agreement on Friday. This removes the prospect of ratcheting up towards a higher rate in future steps – for example, the implementation of the global…