A thick crust of bird droppings is piled on the gilded balustrade of one of Britain's most expensive properties. Pigeon skeletons lie among shattered mirrors and water streams through broken cornicing. This is The Tower, a £30m palace in "Billionaires Row" in north London whose spectacular ruin has been kept secret until now.
It is a desolate scene repeated up and down the supposedly prestigious avenue that Lloyds Bank has calculated is the second most expensive street in Britain. While more and more people struggle to get on to London's property ladder as house prices rise at 11.2% a year, the Guardian has established that 16 mansions on the most expensive stretch of The Bishops Avenue are sitting empty, many behind padlocked gates, with their windows shuttered with steel grilles and overgrown grounds patrolled by guard dogs.
Land Registry records show the portfolio [of the 10 mansions sold last October for a combined £73m] was assembled between 1989 and 1993, around the time Saddam Hussein's sabre rattling in the Gulf threatened the House of Saud. The deal on the boltholes was brokered by Rafic Hariri, the future prime minister of Lebanon, who at that time was working as a Saudi envoy, sources familiar with the transaction say. Five identical mansions were snapped up for £1.5m each along with the palatial Tower – built on the site of the former home of the 1940s film star Gracie Fields – and three neighbouring mansions. But after Saddam was beaten back, the Saudis let dilapidation take hold.
The waste is spectacular. In the grounds, stone fountains crumble and lawns have become bogs. Inside the Georgian mansion water drips through a huge crystal chandelier on to a thick carpet rotting under sections of collapsed ceiling. Moss grows through shattered bricks and mirrored tiles are scattered across a bathroom. An odour of fermentation pervades neighbouring Redcroft and the only signs of life are an old and jammed Arabic Olympia typewriter and a hotel-style sign warning: "Visitors may be asked to submit to a search of person or baggage by security staff." The swimming pool is filled with a foot of brackish water and has flowers growing through its tiles. Wooden slats bulge away from the sauna. Behind the rotting ranch-style shutters of Ilkley House, a tiled peacock remains intact in the pool house but dead plants droop from hanging baskets. A sheaf of invoices reveals a £7,314.54 order for kitchen equipment made in September 1992 including a Robot Juicerator, teak salad servers and a melon baller.
But it is the wreck of The Towers, a grand mansion set in acres of hornbeams, oaks and limes, that is most dramatic, with its huge, high-ceiling halls occupied by pigeons and its walls turned bright green by algae as water pours through three storeys and plinks into a vast, empty basement swimming pool. Unopened wooden crates marked "bullet proof glass" reveal the security fears of the previous owners.