By Mikey Smith Rishi Sunak has “failed to learn from Liz Truss”, Labour said after top Tories floated an unfunded plan to scrap National Insurance which could send mortgage rates skyrocketing. The tax currently raises £46billion – a billion more than the tax cuts announced by the party’s disastrous former PM. Both Chancellor Jeremy Hunt and Treasury minister Bim Afolami have suggested NI could be for the chop if the Tories win the election. But they won’t say when they’d scrap it or explain how they would pay for it, leaving a potential £230billion financial black hole in five years of the nex…