King and Queen giggle as they struggle to cut cake

King Charles III and Queen Camilla made light of their struggle to cut a cake while celebrating the Eden Project's 25th anniversary.

The pair giggled at the Cornwall site as they used a sword to slice the sturdy cake, which was baked to launch preparations for community events in June.

During a tour of the Eden Project's distinctive domed biomes, the King remarked on the many impressive plants, saying "there was nothing" growing when he first visited.

Later, on a visit to nearby St Austell, hecklers tried to question him about Andrew Mountbatten-Windsor and convicted paedophile Jeffrey Epstein – but were told to "shut up" by a woman in the cheering crowd.

The Eden Project's huge domes feature plant life from around the world to highlight humanity's reliance on nature.

As they were shown around the site, Charles, a former Duke of Cornwall, said: "I remember when I first came here there was nothing – amazing how it's developed and grown."

There had been laughter earlier when the King joked about his arrival – his state limousine had made a wrong turn on the sprawling site and disappeared momentarily.

Getting out, Charles quipped: "Now you see us, now you don't."

During the visit, the couple launched the Eden Project's The Big Lunch and The Big Help Out – street party-style events to be held from 5 to 8 June.

As they met volunteers and community groups for lunch, they were tasked with cutting a cake depicting a street party scene.

Colonel Sir Edward Bolitho, Lord Lieutenant of Cornwall, handed his sword to the couple – who perhaps found it a little unwieldy for the job.

Eden Project chief executive Andy Jasper said it had been a great day.

"The King is really interested in how Eden is just growing and he loves the sustainability aspect of this," said Jasper.

"He loves the gardens and he was just telling me how he loves to come back and see how it grows."

Jasper said the King was "very interested" in the site's olive trees, which are thousands of years old.

Charles also appeared to enjoy using a giant "marble" run – which uses wooden balls made from a storm-felled ash tree from the Duchy of Cornwall Estate.

After leaving the Eden Project, the royal couple met community groups at Holy Trinity Church in St Austell.

Charles spoke to teenagers and adults from Young People Cornwall and faith leaders, while Camilla chatted with school children, staff and volunteers from the town's library.

Camilla watched as children from Mount Charles Primary School in St Austell sang Twinkle, Twinkle, Little Star.

The couple then walked a short distance to the Grade II-listed Market House to hear about regeneration plans for the building and local area.

At Market House, the King pulled a pint of the alcohol-free Proper Job 0.5% ale.

As he put the glass up to the tap, he asked: "Is this one of your new ones?"

He was told it was the alcohol-free version of the popular Cornish beer.

Afterwards, they met some of the hundreds of well-wishers who had lined Market Hill to see them.

Andrew Mountbatten-Windsor has denied any wrongdoing in connection with his relationship with Jeffrey Epstein.

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