HIGH winds meant that this precious moment in the 400-year history of the Ashmolean Museum had to be speedily rearranged.

Putting Dr John Hood, vice-chancellor of Oxford University, high above St Giles' with a trowel in his hand, was simply too risky.

So the topping out ceremony marking a key stage in the museum's £61m redevelopment simply became a grand bottoming out, if you will, amid the puddles on the lowest floor.

As guests paddled about, a five-piece brass ensemble performed Handel's Music for the Royal Fireworks, though some thought his Water Music would have been more fitting.

While tempting to curse the weather for robbing us of splendid views that visitors to the museum's rooftop café will eventually enjoy, it was a good time to reflect that gale-force winds had played a big part in blowing together the key elements of this far-reaching scheme.

For, soon after arriving to take over as the Ashmolean's director ten years ago, Christopher Brown was appalled to find winds had blown the roof off one of 'the huts' lying behind the museum's famous neo-classical frontage.

He had been brought in expressly to increase public access to the world's first public museum and ensure the famous collections were better enjoyed and understood.

But, with part of a roof gone and water pouring in, from that time on the director began thinking of expansion on a totally different scale.

"I realised that parts of the museum were not only difficult to live with but required a huge amount of maintenance. So I conceived the idea of a more radical solution."

Guests at the Ashmolean were able to appreciate just how radical last week, for it is difficult to exaggerate the scale of the transformation, which has seen the rear of the celebrated museum demolished (4,614 square metres of the old building to be precise.) The external frame of the new three-storey building that will replace it has just been completed.

And the new extension, due to open in November next year, will provide 100 per cent more display space, 39 new environmentally-controlled galleries, a new education centre, state-of-the-art conservation sudios, study rooms - and a new addition to the scheme, Oxford's very first rooftop café.

With Dr Hood and Richard Gregory, of the construction group HBG UK, unable to pour concrete into the highest section of the building, the task was performed in the bowels of the new structure, containing some 252 concrete piles and 820 tonnes of steel reinforcement bars.

But most of the guests recognised that it was Dr Brown's moment - the director who had discovered the museum as a teenager and has cherished it ever since.

"I first visited the Ashmolean when I was 15," he told guests. "I cycled with a friend from school from Ickenham up the old A40 and we stayed at the Youth Hostel in Headington.

"We were both budding archaeologists. My friend was especially eager to see the Egyptian collections, but, for me, it was the Minoan collections which were the principal draw.

"I was exhilarated, excited and moved to see them for the first time in the Ashmolean."

That summer saw him, trowel in hand, digging with the Oxford professor, Barry Cunliffe, at Fishbourne.

Dr Brown continued to visit while an undergraduate at Oxford, although he admits to having "gone off the rails" by reading history here rather than archaeology.

Remarkably, it turns out that it was the interest that the British security forces took in him that inadvertently brought about his real passion for the old museum "I had been appointed to the staff of the National Gallery, which in the early 1970s was a Civil Service position.

"I had to be security vetted. Because I had been a member of CND it took rather longer than I anticipated. So I spent six weeks in the Ashmolean's Print Room, going through many, many Solander boxes of drawings, first the Dutch and Flemish but then French, English and Italian.

"I think back on that time as a golden moment, exploring the riches of the greatest collection of Old Master drawings in this country, outside the British Museum."

He was to spend 25 years at the National Gallery, where he came to know John Sainsbury (Lord Sainsbury of Preston Candover), with whom he was to work closely on the Dulwich Picture Gallery Trust.

His relationship with Lord Sainsbury was to be highly significant for Oxford. Sainsbury paid a visit to the Ashmolean soon after Dr Brown's appointment to hear the new director set out his ambitious vision.

The Linbury Trust, founded by the Sainsbury family in 1973, was to commit £11.5m to the scheme, allowing the Ashmolean to launch its public appeal.

"John went to Worcester College, just down the road," said the director. "So he knew the Ashmolean well. This project simply would not have happened without John's support."

But the single moment when he realised that his dream would be realised came when the Heritage Lottery Fund announced the award of a £15m grant.

d=3,3,1The Ashmolean remains £15m short of its £61m target, which includes an endowment of £4m to cover future running costs.

With the university soon to announce plans for a campaign to raise £1bn, the Ashmolean, as a department of the university, is likely to be a beneficiary of the massive fundraising.

But its own appeal is ongoing.

Walking around the huge building site with Susan Walker, the Keeper of Antiquities, guests at the topping out were able to see just why the equivalent of seven Olympic swimming pools of earth had to be excavated from the site.

While it still bears a passing resemblance to the Westgate car park, notices on the wall such as "Ceramics" and "Classical Greece" hint at the glories to come.

"Can you go up the ladders and wait in Rome," she called out, as our group marched from the Ancient Near East in tight formation.

From there it was already possible to appreciate the full impact of the great central staircase, already beginning to show signs of elegance.

On every level there will be an introductory gallery telling the story of each floor.

"One of the great problems about the old building was that it was difficult to know where you were in the building," Dr Brown told me.

"One of my key concerns is that visitors should be able to see other galleries, so they know where they are within the building."

So the Rick Mather design will feature a mix of single-height and double-height galleries to create a feeling of extra space.

For too long, the director feared, 'mass collections' have made it impossible to understand the archaeological treasures, unless that is you had the extremely good fortune to have a professor of Aegean on your shoulder.

He is equally passionate about ensuring good access for the disabled. He recalls being stopped as he made his way through the pre-history gallery by a visitor pushing his wife in a wheelchair, struggling to negotiate a step separating two galleries.

"I had not been director for very long. He asked if I was anything to do with the museum and then he gave me a real ear-full, demanding to know why such a great public institution was not accessible for wheelchair users.

"He said it was a scandal. All I could do was say he was right."

For visitors to the new Ashmolean the journey will begin with a 'Crossing Cultures' floor, and the interaction of cultures of east and west during ancient and modern times will be a dominant and ongoing theme.

An 'Ancient World' floor will display objects dating from pre-history to 700AD, while the 'Making of the Modern World' floors will explore the art, religion and ecology of cultures from Europe to the Far East.

For the first time the Ashmolean will be able to display its impressive textiles collection, which the lack of environmental controls had previously made impossible.

The Ashmolean will also at last have a proper loading bay. The days of priceless works of art having to be carried to and from vans parked on double yellow lines on Beaumont Street will end.

A few perhaps may mourn the demolition of the Evans Tram Sheds, created by one of Mr Brown's own boyhood heroes, Sir Arthur Evans, the former keeper of the Ashmolean Museum, remembered for his discoveries at Knossos on Crete.

So would the great archaeologist have approved the buildings he put up to display collections, which by chance has taken place exactly a century after Evans created the Ashmolean Museum of Art and Archaeology in its present form?

"Evans was a contemporary figure," replied the museum director.

"He was, in fact, quite a radical. I think he would have approved. He would have admired the ambition."

No doubt about it. Things at the Ashmolean seem to be bottoming out nicely.