Prince rescues Royal Mum-to-be

Prince William (C) supports his wife Catherine, Duchess of Cambridge as she pulls her heel from a grate during a visit on St Patrick's Day to Mons Barracks in Aldershot, southern England. (REUTERS)

Prince William (L) supports his wife Catherine, Duchess of Cambridge as she pulls her heel from a grate during a visit on St Patrick's Day to Mons Barracks in Aldershot, southern England. (REUTERS)

Catherine, Duchess of Cambridge presents shamrock to the mascot of the 1st Battalion Irish Guards, an Irish wolfhound called Domnhall, as she attends a St Patrick's Day Parade at Mons Barracks in Aldershot, southern England. (REUTERS)

Catherine, Duchess of Cambridge (2nd R) and her husband Prince William (2nd L) pose for an official photograph as they attend a St Patrick's Day Parade at Mons Barracks in Aldershot, southern England. (REUTERS)

Catherine, Duchess of Cambridge smiles during a visit with her husband, Prince William, to attend a St Patrick's Day Parade at Mons Barracks in Aldershot, southern England. (REUTERS)

Prince William (L) supports his wife Catherine, Duchess of Cambridge as she pulls her heel from a grate during a visit on St Patrick's Day to Mons Barracks in Aldershot, southern England. (REUTERS)

Prince William (L) supports his wife Catherine, Duchess of Cambridge as she pulls her heel from a grate during a visit on St Patrick's Day to Mons Barracks in Aldershot, southern England. (REUTERS)

Catherine, Duchess of Cambridge smiles during a visit with her husband, Prince William (3rd L), to attend a St Patrick's Day Parade at Mons Barracks in Aldershot, southern England. (REUTERS)