Deep in southwest London, hidden behind Thames Water’s working pumping station, stands something that will stop you in your tracks.

Kempton Steam Museum is home to the Sir William Prescott Engine – the world’s largest working triple-expansion steam engine, and a machine so tall it would dwarf four double-decker buses stacked on top of each other.

Built in 1927, it once pumped up to 19 million gallons of London’s drinking water every single day. Today, it still runs, and on steaming weekends you can stand right next to it, feel the heat on your face, smell the oil in the air, and watch something truly extraordinary roar back to life.

Its twin, the Lady Bessie Prescott Engine, stands opposite — currently being lovingly restored by our volunteers. Together they sit inside a breathtaking Grade II* listed engine house built from Portland stone, crowned by two soaring chimneys — King and Queen — that have been landmarks across this part of London for nearly a century.

This isn’t a museum of dusty exhibits behind glass. This is living, breathing engineering history — and one of the most remarkable hidden gems in the whole of London. Once you’ve seen it, you’ll wonder how you ever missed it

The musuem is open between March and December every year, with a host of steaming weekends and special events. Head to our Plan Your Visit page for details of upcoming openings.