Heavily pregnant Kate - who is four days overdue - drives away from Buckingham Palace after taking George for a dip in the Queen's pool

EXCLUSIVE: Kate (right), whose second baby was due on Saturday, popped into Buckingham Palace for a dip in the Queen's pool with her son, Prince George, this morning. Accompanied by up to five bodyguards, the royal mother-to-be drove herself in through the gates (left), with her son and what appeared to be his nanny, Maria Borrallo, in the rear of the car. As revealed by the Mail last year, Kate is a frequent visitor to Buckingham Palace's covered pool, used by members of the royal family and staff, where she is teaching George, aged 21 months, to swim. Also pictured (inset): The scene outside the private Lindo Wing at St Mary's Hospital in Paddington, central London, where some royal fans have been waiting for the new baby for more than a week.