London's skyline has been transformed in recent decades - with the Shard, the Walkie Talkie and the Gherkin now among the capital's iconic skyscrapers. The pilots of London's Air Ambulance service have witnessed that change. As the charity marks its 25th anniversary, BBC News took to the skies to get a pilot's eye view of the ever-changing city beneath.
Attempting to commute the 15 miles (24km) from Northolt, west London, to east London's Whitechapel in the morning rush hour in anything less than an hour may sound ambitious. But Pete Driver and Johnny Crewsdon manage it most mornings in less than 10 minutes.
The flight from London Air Ambulance's storage hangar at RAF Northolt to the helipad on top of the Royal London Hospital takes them over a much-changed skyline.
"London from the skies is a very different picture today than it was a decade ago," says Mr Driver. "There are a lot more buildings that pierce through the low lying cloud."
"It's been fascinating to watch the Walkie Talkie take shape," he says of London skyline's latest addition - 20 Fenchurch Street, nicknamed the Walkie-Talkie, because of its distinctive look.
"I've flown in and out of most cities in the world," adds Mr Driver. "London can compete with any of them but it isn't just the manmade structures that defines a city from the air.
"The River Thames is a significant geographical reference for London."
- The Shard, 306m (1,004ft). At 87-storeys it's the tallest building in the European Union and was completed in 2012
- One Canada Square, 235m (771ft). The tallest building in Canary Wharf, completed in 1991
- 30 St Mary Axe, 180m (590ft). Nicknamed the Gherkin, it's not the tallest building in the City of London but probably the most distinctive
- BT Tower, 177m (581ft). The tallest building completed in London in the 1960s, sitting proudly in Fitzrovia
- 20 Fenchurch Street, 160 m (525 ft). Aka the Walkie-Talkie, it was nicknamed the Walkie-Scorchie in 2013 when sun rays reflecting from the skyscraper melted parts of a Jaguar
