The Duke and Duchess of Cambridge had a close encounter with a baby dinosaur and sipped superfruit smoothies on a tour of the world’s biggest indoor rainforest at the Eden Project on Friday.

The surprise visit by Their Royal Highnesses – part of a two-day tour of Cornwall - delighted many thousands of late summer visitors to the home of the famous biomes near St Austell.

The meeting with the dino came at the entrance to the rainforest biome when Eden story-teller Nicole White introduced the couple to a puppet muttaburrasaurus – part of Eden’s Dinosaur Uprising summer show - bringing a big smile to the duchess’s face and leading the duke to give the beast a tickle under the chin.

With temperatures at tropical levels in the biome, the couple cooled off with a few sips from cups of baobab smoothie, a fruit mix made with the African superfruit.

The duke and duchess’s visit was a surprise because they had been due to fly to the Isles of Scilly this morning, a trip which was delayed because of bad weather.

Instead they were greeted on their first visit to Eden by the Lord Lieutenant of Cornwall Col. Edward Bolitho and his wife Alexandra, who introduced them to Eden managing director Gordon Seabright, executive director Peter Stewart and Mike Maunder, director of life sciences.

Under umbrellas due to the soft drizzle, the royal party’s first stop was the viewing platform overlooking the former china clay quarry where they took in the panorama of the rainforest and Mediterranean biomes and education centre the Core.

In the rainforest they walked among papaya and banana trees along the walkway platform, being met by Jo Elworthy, director of interpretation, who informed them about plans to extend the platform along the wall of the biome.

They toured through the citrus groves of the Mediterranean biome before entering the Core, where marketing director Rita Broe showed them an interactive exhibit about the exciting world of electric cars.

On the upper floor, head of policy Augusta Grand informed them about Invisible You, an immersive exhibition revealing the inextricable links between the health of humanity and the planet we inhabit.

Gordon Seabright said: “We were honoured to welcome the duke and duchess on their first-ever visit to the Eden Project. It was a delight for us on a drizzly Friday – as I am sure it was for all the visitors who enjoyed seeing them and in particular those who were able to share friendly chats with them along the way.

“Their Royal Highnesses were particularly interested in our rainforest – the biggest in captivity – and our partnerships across the Commonwealth and beyond. They were also engaged by the fact that we welcome so many schoolchildren, helping them learn about our planet and how we look after it.”