Britain's royal baby countdown begins

The countdown to Britain's Prince William and his wife Kate's third child began today as barriers and parking restrictions sprung up at the London hospital where the royal baby is to be born.

Kensington Palace has not revealed the baby's due date but it was expected that notices would go up around St Mary's Hospital in Paddington a week before the birth, planned at the Lindo Wing where Kate gave birth to Prince George and Princess Charlotte.

The yellow notices put up outside the Lindo Wing refer to an event which will suspend parking on the street from today until April 30.

Some reports have been speculating on the due date being April 23 but Kate, the Duchess of Cambridge, has gone beyond her due date for both her previous pregnancies George in 2013 and Charlotte in 2015 leading to what was dubbed as the Great Kate Wait as journalists, photographers and fans from around the world gathered outside the hospital.

The new child will be fifth-in-line to the British throne, behind big sister Charlotte and pushing uncle Prince Harry one place down the line of succession to sixth.

A change in the law after William, 35, and Kate, 36, were married in April 2011 gave female heirs the same rights of accession to the throne in the UK as men.

Kate suffered from hyperemesis gravidarum, or severe levels of nausea and vomiting, during the early stages of her pregnancy during all three births. Now, the first announcement to come out of Kensington Palace will be to reveal when she has been admitted to hospital for the birth.

A formal signed bulletin will be placed outside Buckingham Palace announcing the news of the newborn after William has informed his grandmother, Queen Elizabeth II, and other members of the royal family once the baby is born.

Britain's royal gynaecologist Guy Thorpe-Beeston will be present for the birth.

As with both previous births, media positions will be clearly marked on the pavement opposite the Lindo Wing doors where Kate and William will emerge with their new arrival.

William and Kate have chosen not to find out if they are having a boy or a girl, but bookies are favouring a girl, with Ladbrokes offering odds of 4/5 it will be another little sister for George.

For a girl, the favourite names are Alice, Mary, Victoria and Alexandra, with Albert, Arthur, Frederick and James as the top choices for a boy.