Families with annual income of up to £120,000 will be able to keep all of their Child Benefit, the Conservatives have pledged if they win the General Election.

The move will leave 700,000 families on the top level salary an average of £1,500 a year better off, according to analysis by the party.

The current rules base entitlement to Child Benefit on the basis of the earnings of a single individual within the household and sets a threshold of £60,000.

Once any parent earns about that figure,…