A 2,400ft jump on to a pile of boxes with no parachute. What could go wrong for stuntman Gary Connery...?

If you happen to be walking in the countryside around Henley-on-Thames this afternoon, look up. You may see a dark shape, soaring through the summer air at 80mph, then gliding like a hawk over the fields and farmland. That would be Gary Connery.

Stuntman Connery, a veteran of nearly 900 sky dives, 450 base jumps and dozens of film and television roles (that's him jumping off the waterfall in Leonardo DiCaprio's film The Beach) will be attempting his most daring feat yet: jumping from a helicopter at 2,400 feet and "flying" in a specially-designed wing suit for nearly a mile before landing on a strip made of cardboard boxes.

"One side of my brain is saying: 'what on earth are you doing?'" he told The Independent on the eve of his jump, which, if successful, will be the first time someone has jumped from such a height, not deployed a parachute, and lived. "But the other side is saying: 'You know you can do this'."

Mr Connery, 42, of Henley-on-Thames, will be in free fall for three seconds before the suit inflates, enabling him to glide, and eventually slowing to around 60mph. After a 1.4km flight lasting a mere 45 seconds, he will land on a stack of 18,600 cardboard boxes, 350ft long, 50ft wide and 12ft deep. No sweat.

An ex-paratrooper and father-of-two, Mr Connery admits to being " a bit scared". For a man who has jumped off Nelson's Column, the London Eye and the Eiffel Tower, that is saying something. For safety,he will have a parachute on him, but, as he makes very clear, "the intention is not to deploy it".

"I'm sure everybody has experienced something where they were afraid, and questioned why they were doing it," he said. "But there's something special about overcoming fears. When you complete a stunt and the job is done, a feeling of euphoria builds up inside of you. It feels like... if you can imagine a crushing blow, but in a really nice way. I suppose it's adrenalin but I don't want to be labelled an adrenalin junkie."

Bearing in mind that later today he will be hurtling through the air at 80mph, 2,000ft above Buckinghamshire, it is hard to take him at face value on that one.

But however intense the sensation might be, Mr Connery insists: "I don't go chasing that feeling. I'm not about the numbers – how high, how fast, how many jumps. I want to share my experiences with as many people as possible. I want them to be inspired by what I am doing to do something in their own lives."

Mr Connery admits that his wife, Vivienne, and children Kali, 15 and Lydia, 19, "probably worry" about him. But Vivienne at least knew what she was getting herself in for.

"I met my wife on a beach, with a parachute on my shoulder, having just landed from a base jump," he recalls. "So she knows what I'm about. The kids have grown up with it. They are at the age when they wouldn't say so, but I think what I do inspires them too."