By Emma Revell The UK hobbles not just financial services but any business operating on the London stock exchange by levying a tax on share purchases, writes Emma Revell Say you wanted to boost investment in UK-based companies. And people’s pensions pots to be larger. And the valuations of British companies to be higher. And to make the City of London more competitive. And to increase liquidity in the markets. And to do it all without costing the Treasury any money – in fact, probably boosting the tax take in the process. Sounds like a pipe dream, doesn’t it? But there’s a simple step that Jer…