Tony Blair and Gordon Brown embarked on a PR offensive yesterday in a bid to sell tax increases to a sceptical public.

The prime minister - who was accused of scoring an "own goal" by increasing the national insurance liabilities of the NHS and its workers - has written to Labour MPs asking them to promote the UK as a low-tax economy.

Gordon Brown insisted yesterday that the tax was being levied in "a fair way". But he had earlier conceded that Wednesday's announcement was "a gamble politically".