Image copyright Reuters Image caption The Queen handed the baton to athletes and attended a ceremony at Westminster Abbey.

The Queen has started the countdown to the 2018 Commonwealth Games, launching the baton relay at Buckingham Palace.

She handed the baton to two-time Olympic champion cyclist Anna Meares on Monday as it started its journey to host country Australia.

The relay will span 388 days, 71 countries and more than 200,000 miles before reaching the Gold Coast.

The Queen and other Royals marked Commonwealth Day with a service at Westminster Abbey.

The games begin on 4 April 2018.

Australian Paralympian Kurt Fearnley brought the baton to the palace before it was given to the Queen.

After placing a message inside, the monarch then handed it on to his fellow countrywoman Meares.

She was joined by her former rival and now friend, Team GB champion cyclist Victoria Pendleton, to start the first leg of the relay.

Image copyright PA Image caption Athletes from Australia and Britain came together for the ceremony

"Being a former athlete, the Commonwealth Games are very special," said Meares. "They are something that you work very hard for, but you only get the chance to compete once every four years. When the Queen's baton starts, you get a little flutter in your chest as you knew it was getting close.

"The Gold Coast, with its iconic beaches and the Australian lifestyle, they are just waiting and itching to welcome the world there. It is the biggest sporting event of the decade for our country and the anticipation is building."

Queen's commitment to Commonwealth unwavering

By Peter Hunt, BBC diplomatic and royal correspondent

Image copyright EPA

As she stood on the makeshift stage in the Buckingham Palace forecourt, the Queen might have been tempted to reflect on one of the benefits of longevity.

Her commitment to the Commonwealth has been unwavering; that of her ministers, in the past, less so.

Take Ted Heath. For him, in the 1970s, the Common Market trumped the Commonwealth.

Other prime ministers have been wary of a loose affiliation of nations that battled against apartheid in South Africa but which have, sometimes, struggled to uphold principles of accountability and respect for human rights.

But post-Brexit, the club of 52 countries is taking on greater significance for the UK government.

The Commonwealth makes up a relatively small part of UK trade. As we leave the European Union, Number 10 wants to increase exports to these countries.

Where the baton is headed over the next 388 days, will British goods, in greater numbers, one day follow?

Pendleton added: "It is an honour to be recognised and be asked to participate in something like this. There will be lots of people on the route who have volunteered... and it will be their way of connecting with the whole Commonwealth Games and what it means to people.

"It is the first time I have been part of a Queen's baton relay so for me it was... a massive honour."

School children from all of the countries represented at the games were also at the event and there was a performance from Australian singer Cody Simpson.

Media playback is unsupported on your device Media caption The designers of the baton, Alex Wall and Warren Shroeder, tell the BBC how it reflects the host region of the Gold Coast.

The Commonwealth Day service at the abbey was also attended by the monarch, the Duke of Edinburgh, the Prince of Wales, the Duchess of Cornwall, Prince Harry, the Duke of York and the Earl of Wessex, as well as Prime Minister Theresa May.

Olympic gold medallist Jessica Ennis-Hill brought the baton into the abbey at the start of the ceremony.

Image copyright AFP/Getty Images Image caption Jessica Ennis-Hill also took part in the service

The multi-faith service saw performances from a range of musicians from across the Commonwealth, along with speeches from religious leaders.

This year's theme was "a peace-building Commonwealth".

Image copyright Getty Images Image caption Prince Harry attended the service at Westminster Abbey.

In a message to the 2.4 billion Commonwealth citizens, printed in the order of service, the Queen wrote: "The cornerstones on which peace is founded are, quite simply, respect and understanding for one another.

"Working together, we build peace by defending the dignity of every individual and community.

"As members of the Commonwealth family, we can find much to be thankful for in the inheritances we have received from those who came before us. Through consensus and co-operation, great things have been achieved."

Commonwealth secretary general Baroness Scotland also gave her own Commonwealth Day message, read at flag ceremonies around the country.

She said: "By linking governments and institutions - both public and private - and bringing together in a spirit of goodwill people of all ages and from all walks of life, Commonwealth gatherings and networks lay foundations of respect and understanding that enable lasting peace to be built."