Child number three '˜just a happy event' for Kate and Will

It was announced earlier this year that as the Duke of Cambridge gave up his job with the East Anglian Air Ambulance, the plan was for them to spend more time in London and increase their number of engagement – especially with the announcement earlier this year that the Duke of Edinburgh would retire from solo royal engagements.

It seemed, therefore that this plan had gone awry .

After all, the Duke and Duchess are a couple with two children already: a boy and a girl, and it seemed their family was complete.

Indeed, I was asked in an interview if there is a protocol involved in royal family planning: if there are any rules around how many children members of the royal family are allowed to have, and how they should be spaced out.

Although the Queen has four children, this is not a guide, with the ten year gap between Princess Anne and Prince Andrew caused by the Queen’s accession to the throne aged 25.

They will be the first of her descendants to have more than two children: each of the Queen’s children have two children each. Of her eight grandchildren, Peter Phillips has two children, Zara Tindall has one and the Duke and Duchess of Cambridge now expect their third. This child will be fifth in line to the throne.

It would seem, there is nothing more to this happy announcement than that they wanted another child and are now expecting one.

As with Prince George and Princess Charlotte, Kensington Palace was forced to release the news earlier than the 12-week mark because the Duchess had to cancel two engagements. She is again suffering from hyperemesis gravidarum – severe morning sickness.

This indisposition caused her to miss Prince George’s first day at school – something I am sure she would have been loathe to miss. In his first engagement since the announcement, the Duke spoke of anxiety at the Duchess’s condition but how there would be celebration later.

The Duke and Duchess and their family have proved very popular with people of all ages. I was at the Trooping the Colour ceremony earlier in the year when they brought out the children on to the balcony at Buckingham Palace.

The cheers from the crowd became deafening as soon as the children appeared. The future of the monarchy seems to be in safe hands.