The Queen heard a dire warning about the state of the world’s oceans as she led the nation in marking Commonwealth Day.

With her family gathered around her, the Queen joined the 2,000-strong congregation at Westminster Abbey to honour the family of nations which is celebrating its 70th anniversary this year.

Endurance swimmer Lewis Pugh gave the reflection and urged the Commonwealth to lead the world in ocean conservation, and combat the threat posed by the “perfect storm” of climate change, over-fishing and plastic pollution.

The Prince of Wales, Duchess of Cornwall, Duke and Duchess of Cambridge, Duke and Duchess of Sussex and the Duke of York were among the guests, with the Prime Minister, Theresa May, High Commissioners and hundreds of schoolchildren.

The royal women looked stylish with Meghan, in a Victoria Beckham outfit, warmly exchanging kisses on both cheeks with Kate who was dressed in Catherine Walker, while Camilla wore Bruce Oldfield and the Queen was in an Angela Kelly ensemble.

The Commonwealth plays an important part in the public life of the Queen, who famously dedicated herself to the empire on her 21st birthday in 1947.

Now head of the Commonwealth, the then Princess Elizabeth said that day: “I declare before you all that my whole life, whether it be long or short, shall be devoted to your service and the service of our great imperial family, to which we all belong.”

In her message to mark Commonwealth Day, the Queen praised how the family of nations inspires its member states to find ways of protecting the planet and its citizens.

Millions of people are “drawn together” because of the collective values shared by the institution, the Queen said in her address.

Commonwealth Day 2019
The Duchess of Sussex and The Duchess of Cambridge leave the Commonwealth Service at Westminster Abbey (Kirsty Wrigglesworth/PA)

The modern Commonwealth was established in 1949 when eight countries – Australia, Britain, Ceylon, India, New Zealand, Pakistan, South Africa and Canada – signed the Declaration of London.

Within a few decades, it had expanded rapidly and today has 53 member states.

In past years, some commentators have criticised the Commonwealth for its apparent weakness and ineffectiveness when dealing with member states who do not abide by the rules.

But supporters of the family of nations believe it allows countries to unify on common causes and ultimately, through unity, effect change.

Mr Pugh, UN patron of the oceans, told the congregation about the scale of the problems facing the planet: “The speed of change is alarming. When I first swam in the Arctic the water was three degrees centigrade – when I swam there recently it was 10 degrees centigrade, and that is right on the edge of the Arctic icepack.

“What we are now doing to the world will impact every single person on this planet, it will impact every future generation and impact the whole of the animal kingdom.”

He said that “our common wealth is our oceans”, adding: “Now is the time to build a new generation of green protected areas and now is also the time to welcome in a new generation of marine protectors.”

The swimmer ended with the words: “It’s the moments which challenge us the most that define us.

“We stand at a crucial moment in the history of our planet so must dive in together, and without reservation, in order to protect our oceans – let this be the Commonwealth’s gift to the world.”

Commonwealth Day 2019
Members of the Royal family watch a performer during the Commonwealth Service (Kirsty Wrigglesworth/PA)

During the event, the guests were treated to a range of musical styles reflecting the peoples of the Commonwealth from a didgeridoo performance and the deafening sound of north Indian drumming to tenor Alfie Boe singing Run by Snow Patrol.

Boe said after his performance it was an honour to perform for the Queen and said Harry and William were “very complimentary”.

He added: “They were talking about how powerful my voice was and how standing on the sanctuary without any accompaniment and any amplification it was very impressive – I was more nervous than impressive I thought.”