The reality is that the large US tech giants this is aimed at are essentially mercantile companies. Paying little or no UK tax on significant UK revenues, which

The reality is that the large US tech giants this is aimed at are essentially mercantile companies. Paying little or no UK tax on significant UK revenues, which are then remitted via tax efficient structures to the US parent. Profits are a Will-o'-the-wisp which appears and disappears in whatever tax jurisdiction is most efficient at the time. For this reason I don't see corporation tax (which is <10% of total tax receipts) being something future governments can count on (unless that government is home to the mercantile company). TLDR: Find somewhere else to get the 9%.