William and Kate's third baby to be born in St Mary's Hospital

Duke and Duchess of Cambridge with their son Prince George of Cambridge in 2013. Picture: PA Wire

The palace announced in October that the baby was due in April, and while the precise date has never been confirmed, the baby might put in an appearance around April 27 or 28.

The Lindo Wing at St Mary’s Hospital is a private facility offering “world-class maternity care”.

Kate’s first two children, Prince George and Princess Charlotte, were born in the exclusive unit in Paddington, central London, as were their father, the Duke of Cambridge, and uncle, Prince Harry.

The Duke and Duchess of Cambridge greet the media after the birth of their first child, Prince George. Picture: PA Wire

William made his public debut with the Prince and Princess of Wales outside the hospital, wrapped in a white blanket and carried in Diana’s arms, with Charles by her side.

Only a handful of midwives and medical staff, led by consultant obstetrician Guy Thorpe-Beeston, were in the delivery room to supervise Charlotte’s birth but waiting in the wings were more than a dozen experts in case of emergencies.

Theatre staff were on stand-by along with a lab technician, replacement anaesthetists and paediatricians - 23 in total - from Imperial College Healthcare NHS Trust, which runs St Mary’s Hospital.

In the Lindo Wing, Kate will again be given a bespoke experience akin to a five-star hotel with en suite rooms available “providing a modern, homely environment in which to start your new or expanded family life”, the unit’s website states.

Kate and William with the Princess of Cambridge in May 2015. Picture: PA Wire

Deluxe rooms and suites are also available.

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The latest price list, from July last year to March, states that a standard room package, including a one-night stay, costs from £5,900, while a deluxe package is £6,275 - with an extra night priced at more than £1,000 for both options.

The price of a suite of two rooms, with one used as a living room, is available on application but five years ago it cost £6,265 for a one-night stay.

With standard and deluxe care packages rising by around £1,000 since the birth of their first child, William and Kate could spend close to £7,500 for a suite.

Each room has a satellite TV with major international channels, radio, bedside phone, fridge, free wi-fi and a choice of daily newspapers.

All meals are freshly prepared in a dedicated kitchen and there is even an afternoon tea service, for parents to celebrate their new arrival, the website suggests.

The Lindo Wing’s internationally renowned obstetric unit caters for complex pregnancies and deliveries as well as multiple births and it has the benefit of being based in an NHS hospital if further complications arise, including its facilities for premature babies in the Winnicott Baby Unit.

In 2006, William visited the refurbished NHS neonatal unit at St Mary’s, cradling two tiny premature babies - one weighing just 5lb.

At the forefront of specialist care for premature babies, the Winnicott looks after some of the most critically ill newborns in the UK.

It treats around 350 sick and premature babies from across the country each year, caring for up to 18 infants at a time.

Diana returned to St Mary’s in April 1997 - four months before her death in a Paris car crash - when she toured the paediatric intensive care unit, meeting poorly youngsters.