To you and 2.4 billion others: Happy Commonwealth Day

The Queen will be leading Commonwealth Day celebrations. Credit: PA

It might not trip off the tongue in a way in which St Andrew’s Day might in Scotland (or St George’s Day in England, St David’s Day in Wales) but today is Commonwealth Day.

So, Happy Commonwealth Day to anyone reading this.

You’re sharing the celebrations with almost a third of the world’s population.

Because the Commonwealth, the group of countries formed after the demise of the British Empire, has 53 member states in which 2.4 billion people live.

Which is quite something.

And the Queen will lead those celebrations this afternoon at a service at Westminster Abbey.

She’ll be joined by her children, Charles, Andrew and Anne, as well as her grandchildren.

Meghan Markle will also be there as she embarks on her first official engagement with her fiance’s grandmother before her wedding to Prince Harry in Windsor in May.

Prince Harry's fiancee Meghan Markle will also be attending the service. Credit: PA

It’s often asked how counties once ruled as a British colony ever agreed to join a club in which the former colonial ruler was a key member.

And the answer is in large part down to The Queen.

She has been the Head of the Commonwealth since 1952, then aged 26, and she has worked hard to expand and grow the organisation ever since.

The club has been successful because it is bound by historical and current ties: The Commonwealth Games get underway in Australia at the end of this month, the Commonwealth Heads of Government Summit takes place in London next month (it could be the last one the Queen ever goes to).

Flags on display at Parliament Square in during Commonwealth Day in 2017.

The Queen always speaks of a focus on what these diverse countries have in common rather than how they differ.

In her message this year, she spoke of how the organisations helps others to "see life from other perspectives".

Some of the member countries are obvious: Canada, Australia, India.

Others less so: Rwanda, Papua New Guinea, and Namibia.

Not every leader of every country is always happy with being a member.

Recently, The Gambia re-joined The Commonwealth after its former president walked away in 2013 calling it a “neo-colonial institution”.

The Queen and Duke of Edinburgh pictured on a visit to The Gambia in 1961. Credit: AP

But today, the Queen will look to the organisation’s future.

Prince Charles might be its next head when he becomes king - if its members agree.

And the leaders of the 53 countries will discuss that sensitive topic in the margins of April’s summit.

Prince William will be there today. Last year he was criticised for choosing a lads’ weekend away in the Swiss ski resort of Verbier instead of the Commonwealth Day service.