National insurance, with its multiple thresholds and rates and P11 forms, is a nightmare to administer for a business and keeps hoards of civil servants in work. Replace it with a simple fixed-rate payroll tax (or better, don't replace it with a simple fixed-rate payroll tax) and an uplift to income tax.
Why does this idea matter?
Come on, nobody seriously believes that this tax is hypothecated to pay pensions, do they? It's a fairy tale tax that's impossible to administer.