An iconic red double-decker bus is the centrepiece of a superb collection of London-based artefacts coming to auction at Christie's.

The 1966 Routemaster will arrive at the September 3 sale with a £20,000-30,000 estimate and is one of 150 lots that will celebrate "art and icons of the capital".

The original Routemasters, much-loved for their open rear platform and conductors, were phased out during the 1990s and 2000s, and now ply their trade on just two heritage routes.

Original Routemasters are seldom seen on London's roads

Originally from Lincolnshire, but best known for the time she spent in residence at London's Downing Street from 1979 to 1990, three dresses believed to have been worn by former British prime minister Margaret Thatcher during the 1970s will also auction.

Each has an estimate of £1,000-1,500, which could be a conservative one, considering a handbag that once belonged to her made £25,000 in 2011. We are currently able to offer a wonderful signed photo of the Iron Lady from her student days at Oxford.

Several works of art will also feature, including John Atkinson Grimshaw's £150,000-200,000 valued St Paul's Cathedral, from the River Thames, produced in 1883.

Edward Seago's The Quadriga, Hyde Park Corner will appear with a £80,000-120,000 valuation.

A number of vintage travel posters of the capital will also feature, including Norman Wilkinson's view of the Houses of Parliament, produced in around 1930, which has a £3,000-5,000 valuation.

"We hope that London residents and tourists alike will enjoy visiting the exhibition and learning a little more about London's rich history through the objects and works of art on offer," commented Nick Martineau, the head of the sale.

The pieces will be on display at the auction house from July 27.