Sellar tops out his towering ambition On the day before the official launch of the Shard, Irvine Sellar, its developer, is searching for the right sporting analogy to sum up the project that has dominated the past 12 years of his life. "It's sort of like swimming all the way across the Atlantic," he says, echoing the self-aggrandising puff routinely spouted by property developers. But there is no need to use sporting references to explain a building which speaks so eloquently for itself. The Shard is unlike any other building in the country. At 310 metres, it shoots up from the roof of London Bridge station to tower over the capital, its glass-clad structure narrowing as it climbs, ending in a series of broken points. The idea, which will be put to the test when a laser show marks the completion of external work at 10pm on Thursday night, is that it should melt seamlessly into the clouds. In reality, its bold, upturned icicle form puts the sobriety of London's skyline into stark perspective. It nearly didn't happen, though. In 1998 when Mr Sellar bought Southwark Towers, which used to occupy the site of the Shard, the purchase was intended as a long-term investment. However, he changed his plans in 2000 when the Labour government warmed to ambitious property developments in central London. Realising he would need a famous architect if he were to have a hope of convincing planning authorities of the need to have a skyscraper in an otherwise low-slung part of London, Mr Sellar flew to Berlin to have lunch with Renzo Piano. The Italian architect best known for Paris" Pompidou Centre was initially unimpressed with the idea, dismissing tall buildings as architectural statements of arrogance. Relenting, the architect flipped over the menu and quickly sketched the outline of the now finished building. Sitting in the 14th-floor marketing suite, Mr Sellar concedes that it was a strange task to undertake. The view from this height isn't impressive - the elevation no longer remarkable in a city punctuated by tall buildings - but the complexity of the scene below takes a moment to absorb. The narrow strip between the building and the river Thames is lacerated by railway lines. The tracks coming out of London Bridge station curve sharply round its base before straightening out in silvery pencil lines towards Kent and the south coast. Things happen by accident. We bought a building for rent and we ended up with the hardest site in London to develop, but you just have to stick with it," he says doggedly. It is this stickability that has got the Shard to where it is today. The project nearly went off the rails altogether at the start of 2008, when construction finance dried up. It took a last-minute deal with a consortium of Qatari investors to swap an 80 per cent stake of the Shard for £150m to keep it going. Despite the Qatari's majority ownership, Mr Sellar has remained firmly in the foreground, squaring up to those in the property industry who doubt he will be able to achieve targeted rents of £50 to £55 per sq ft for the 26 floors of offices at the bottom of the building. Transport for London, which had signed a 200,000 sq ft pre-let agreement at £38.50 per sq ft in 2006, was bought out in 2010 in the hope that higher rents could be achieved by letting smaller suites. "It's a beautiful building to look at from the north side of the river, but office tenants are not going to pay what they would pay in the City - it's just not realistic," says one senior central London estate agent. Mr Sellar, however, remains confident that the building will achieve its potential. "We're not under any time pressure to find tenants," he says assuredly. The luxury residential flats will not even be marketed for a few years, as Mr Sellar wants "the brand of the building to get established first." "I knew when I took this project on that it would be like going a full 12 rounds in the boxing ring," he says. I might have a couple of bad rounds in there, but I have come back fighting every time and I will keep doing so.