“Every single pledge we make comes with a price tag attached and a clear plan for how that cost will be met,” Gordon Brown declared in his conference speech on Tuesday.

Some promises cannot yet be priced, however, such as the cost of raising the minimum wage, child benefit and child tax credits. Others, such as restoring the earnings link with pensions, can be broadly estimated – perhaps £700m ($1.1bn) in the first year and £1.3bn in the second, depending on the gap between earnings and prices at the time.