Construction work on the first 50m Olympic-sized pool to be built in London for more than 40 years has reached the topping-out phase.

The £25m complex is due to open in early 2010 and is part of a large redevelopment of sports provision in the London Borough if Hillingdon, which also involves the complete refurbishment of a 1930's outdoor lido and an athletics stadium, sports hall and fitness centre.

The 50m pool will include a movable floor, allowing for the space to be used as two 25m pools for different uses, as well as altering the depths according to use.

The development is being built next to the 1930's Uxbridge open-air pool, a Grade-II listed building, which is also being refurbished.

The project has been funded by Hillingdon Council (£22m), the London Development Agency (£2.025m), Sport England (£1.5m) and the Heritage Lottery Fund (£1m).

Henry Higgins, cabinet member for culture, sport and leisure at Hillingdon Council, said: "We can't expect to encourage future Olympic hopefuls and get people living more active lifestyles if we don't invest in providing facilities that inspire people and provide high-quality resources in their local area.

"The sports and leisure complex in Hillingdon should do just this, and with the refurbishment of the 1930's lido as well, we're bringing an important part of history back to life that can be enjoyed by all ages."

Hillingdon Council has employed Leadbitter for the construction of the site.