Tory grandees who served in Margaret Thatcher’s final cabinet have warned that the former prime minister would never have approved of Liz Truss’s plan to slash £30bn off taxes funded by borrowing, as Rishi Sunak denounced his opponent’s plans as “immoral”. With a bitter row over tax emerging as the defining issue in the race to succeed Boris Johnson, three members of Thatcher’s cabinet told the Observer that she would have taken a dim view of slashing taxes at a time of high inflation.This follows repeated claims that Truss has attempted to model herself on Thatcher in her attempt to win the leadership, which she has denied.