London, England (CNN) -- Prince William's younger brother Prince Harry will be his best man when he marries Kate Middleton in London in April, Clarence House announced Monday. Middleton's sister Philippa will be her maid of honor. 

William, who is second in line to the throne, is due to marry his long-time girlfriend April 29 at Westminster Abbey. Prince Harry is currently third in line of succession. 

Royal protocol states that the groom should have a "supporter" rather than a Best Man and speculation was rife that Prince Harry would be named supporter, and another friend of Prince William announced as his best man. 

Prince Charles elected his brother Prince Andrew to be his "supporter" when he married Diana, Princess of Wales in 1981. 

Naming Harry best man is a break with protocol, and is being taken as an indication of William and Kate's more modern approach to their upcoming wedding, which is taking place at Westminster Abbey on April 29. 

Harry will be organizing the Prince's "stag" or bachelor party. Meanwhile Philippa, or "Pippa," will be expected to pull together Kate's "hen" or bachelorette party. 

William's office at Clarence House also announced that there will be four bridesmaids and two page boys, including two of William's godchildren. 

They are Grace van Cutsem, 3, and Tom Pettifer, 8. Pettifer is the son of Tiggy Pettifer, William and Harry's former nanny -- an important figure in the young Princes' lives, especially following the death of their mother in 1997. 

Lady Louise Windsor, 7, the Hon. Margarita Armstrong-Jones, 8, and Eliza Lopes, 3, will be the other bridesmaids. 
When did Diana pass away?
the death of their mother in 1997. 