The May blossom is out, the countryside is lush and a glorious fragrance suggestive of spring fills the air – in other words it’s time to brush the dust off the picnic basket and consider eating al fresco. Having bought myself a picnic rucksack that keeps cold food cold and hot food hot and comes complete with food containers, wine holders and even a bottle opener and wine stopper, I have been spending some time considering what would constitute the perfect picnic.

It was my friend Rupert Ponsonby, the ideas man and director of R & R Teamwork, who suggested that the ultimate picnic had to take place at the point where the Oxfordshire and Gloucestershire boundaries meet. He went on to suggest he could arrange for me to participate in a picnic I would never forget.

As Rupert has invited me to several really wacky and memorable meals over the years, I took his invitation seriously, little realising that he was offering me a hot-air balloon flight over the Cotswolds that was destined to reach a height of 10,000ft – almost two miles! The purpose of the flight (oh yes, his ideas always have a purpose) was to observe the bubbles in various Taittinger champagnes during altitude changes.

The passengers would be asked to monitor the way in which our sense of taste changed at altitude and note whether the change in pressure affected the size, speed and number of champagne bubbles. Only Rupert could have possibly come up with an idea like this.

How on earth could I pass up such an invitation? Impossible. My only regret was that I couldn’t take the dog – but I doubt he would have enjoyed it as much as I did.

So there I was, standing on the lawns of the Bibury Court Hotel, in Bibury, glass of champagne in hand, watching the pilot and his assistant blowing hot air into our balloon so that we could reach the heights.

There were only three of us joining the pilot Pete Dalley: myself, scientist Margaret Everitt and Mark Rock, a photographer who specialises in photographing wines and spirits.

We had been given a glass of the Taittinger Comtes de Champagne Blanc de Blancs 1999 as a starter, while on the ground. As this gold medal winning champagne costs £140 a bottle and makes your toes tingle within seconds of taking the first sip, we raised our glasses to the forthcoming flight with a strange confidence that comes from consuming bubbles of that magnitude.

After clambering into the basket, glass in hand, we gradually ascended towards the heavens. It was like nothing I had ever known. I hadn’t realised just how silent it would be when the fire wasn’t being injected into the balloon. No bird song – nothing just a deep silence, broken only by the pilot reaching for the first bottle we were expected to taste. It was a non-vintage Brut Reserve, Taittinger’s most popular champagne. We had reached 2,000ft and still had 8,000 to go. Even so, on examining her glass Margaret got really excited as the bubbles were already palpably larger.

When we tried the Taittinger Prestige Rosé next, at the height of 3,000ft, she became positively ecstatic. “Look at the bubbles now!” she exclaimed. We looked, we drank and embraced her enthusiasm.

As the balloon began the final ascent and we were close to 10,000ft, Pete poured us another glass of the 1999 vintage that we had tasted before take-off. By now the air was cooling down, so were we. The drop in temperature was affecting this champagne, but the bubbles were still large and sparkling.

Having examined the glass and taken a sip, Margaret looked across at me and asked if I was really going to spit it out as all good tasters are supposed to do.

I looked at my glass, looked at her, then raised my glass to the heavens and downed the lot. She followed suit. Well how many times do you find yourself holding a glass of one of the most superb champagnes in the world while travelling at 10,000ft? We could not possibly let the moment pass.

The landing was fun, the basket tipped over and rattled over the grass, leaving us all tangled up in a mass of twisted arms and legs – but still laughing.

A group of young farmers who had watched our decent into their meadow reached us in their 4x4s as we untangled ourselves. “Welcome to Germany, you have landed just outside Berlin” they announced with a laugh.Our ‘retrieval-car’, which had been following the balloon and was carrying the picnic basket, sped across the meadow seconds later.

We were still sipping champagne and munching on asparagus rolls, smoked salmon sandwiches and sushi as dusk began to fall and the moon rose to cast its magical, mystical light over our picnic party. Yes, Rupert was right: this really was the ultimate picnic and one I will never forget.