"Government needs to dial back the attack on the individuals doing the work and focus on updating the income tax and NICs regimes to better reflect the modern world."
Absolutely - governments should stop the attack on individuals who do the work and focus on updating the income tax, NIC and pension regimes to reflect the modern world - and view those as a package: final salary pensions for some groups of public sector workers have a value that is not available to other employees either (most of whom are on defined contribution schemes), and should be factored in, as should the value of holiday pay, sick pay, training, and all/any other benefits. When you have some public sector employees who are on final salary pensions (with contributions not just matched but matched four times over) complaining about contractors being paid a lot, yet using contractor rates as an argument for their own pay rises because it's unfair contractors are paid more, something is wrong - that is a direct, "real world" example, by the way
Put the value of those benefits on top of base pay, and use that gross as the salary when making the total income calculations - then just set a tiered but simple tax system, no exemptions, no-one can claim expenses or receive benefits that others don't get unless it's calculated in, with no way to use dividends as income unless everyone can do it, and absolutely no scope for lawyers to game the system. Almost as important, do it as an all in one exercise - either they do all of it, or they stop tinkering with things as they are until they've come up with a coherent and simple system that is fair to all, balancing rates and rights, risks and rewards.