The Eden Project reached an astonishing milestone in its short history when it welcomed its 10 millionth visitor on Tuesday.

Entering together were husband and wife Jonathan Shaw and Sarah Klaes from Banbury, Oxfordshire, who were greeted at the ticketing hall of the former china clay quarry at Bodelva, near St Austell, Cornwall, by Eden's chief executive Tim Smit.

Tim presented the couple with lifetime memberships to Eden and a complimentary meal for two as their prize.

He said: "It was a pleasure to gently surprise Jonathan and Sarah with the happy news. We're not that far past our seventh birthday and to have already welcomed such a vast number in that time is mind-blowing and not a little humbling.

"Our aim is that every visitor should enjoy these amazing surroundings and perhaps learn a little more about how to walk lightly on the planet. We certainly hope they feel more optimistic and empowered when they leave."

Tim Smit, Eden Project: "We're not that far past our seventh birthday and to have already welcomed such a vast number in that time is mind-blowing and not a little humbling."

Sarah, an environmental educationalist, and Jonathan, who runs his own computer company, are on holiday in Cornwall, staying in their camper van in the Newquay area.

Sarah said: "Wow - this is a total surprise and a really happy one. I've been to Eden once before, as the major event of my hen party in April of last year. I've been really looking forward to bringing Jonathan here so we could see it together."

Looking over Eden for the first time, Jonathan said: "What an amazing environment. For years I've been looking forward to seeing the project close up after hearing so much about it. What a surprise!"

Since fully opening in March 2001, Eden has generated more than £800m for the regional economy and employs nearly 500 staff. Beyond Eden, it is estimated that 3,000 jobs have been sustained due to the project's continuing success.

On an annual basis, Eden generates around £80m for economy, with the benefits felt by the project's 2,500 local suppliers and a range of other businesses outside including hotels, restaurants, bed and breakfasts, pubs and taxis.

The latest Cornwall Visitor Survey found that Eden remains one of the main reasons why people visit Cornwall, with nearly four out of ten people coming to the county intending to go to Eden.

Figures recently made public by the Association of Leading Visitor Attractions showed that Eden is now seventh in the national ALVA table of attractions where people pay to enter.

Tim said: "We continue to rub shoulders with some big attractions in or near major cities that have been around a long time. The fact that we are at the end of the country and just out of our infancy makes the 10 million milestone all the more remarkable."

He added: "We now look forward to welcoming number 20 million!"