THE Duke and Duchess of Cambridge’s first child is set to push Prince Harry into fourth place in the line of succession to the throne - even if they have a girl.

Prince William and Kate’s child would move into third place, become more important than Harry and not be subject to the centuries-old law of primogeniture, which puts male heirs ahead of women. He or she will leapfrog Harry by being be the first born of first-in-line Prince Charles’s first son.

It is anticipated that Harry and Pippa Middleton could be asked to be the child’s godparents, if the royal couple follow the tradition appointing the best man and maid of honour from their wedding.

The baby will be third in line to the throne regardless of gender after Prime Minister David Cameron agreed a deal with other Commonwealth countries to change the rules on the royal line of succession which means male heirs will no longer be given priority.

This means that in the 15 other countries where the Queen is head of state the rules must be changed. It had been feared there could be a constitutional crisis if the Royal couple had a baby girl before the law was changed.

But today’s announcement that the Duchess of Cambridge is expecting the couple’s first child - third in line to the throne - has come after the deal was agreed.  In October 2011, David Cameron announced that the 16 Commonwealth countries where the Queen is head of state had agreed to give female royals the same rights of succession as their brothers.

‘Put simply, if the Duke and Duchess of Cambridge were to have a little girl, that girl would one day be our queen,” Mr Cameron said.

Under the ancient rules of male primogeniture, first born royal daughters in direct line to the throne were leapfrogged by their younger male siblings.

The principle was criticised and widely viewed as outdated and discriminatory.

The current law of male primogeniture only allows Elizabeth II to be queen because she did not have any brothers.

Moves towards constitutional change gathered pace in the wake of the Duke and Duchess’s wedding in April 2011 in anticipation they would produce an offspring.

Mr Cameron had previously warned it would take time due to on-going negotiations with the Commonwealth countries where the Queen is also head of state, but at the Commonwealth Heads of Government Meeting in October 2011 he confirmed the changes would go ahead.

Downing Street said any attempt to alter the law would be a ‘difficult and complex matter’, with parallel legislation needed in all such Commonwealth nations.                                –DM