I don’t believe the previous government had planned to spend that, because that would mean having a plan.

I expect it just wasn’t costed in a way that made the actual costs apparent. Labour will have made sure to get everything even tengentially related into that figure, whereas the Tories will be inclined to spread the cost over as many department budgets as possible.

None of this is excuse or justification. It’s a brain dead policy, and it looks like the Tories were blind to how much it was costing. Whether they were willfully blind or not is only difference between incompetence and corruption.