The 150-year-old water pumping engine, which was originally used to deliver clean drinking water to reservoirs near Notting Hill Gate is three floors high and weighs several hundred tons.  During the afternoon, Professor Isobel Pollock, Chairman of the Institution of Mechanical Engineer’s Heritage Committee, will present an Engineering Heritage Award in recognition of the engine’s significant mechanical engineering importance.   

The Bull engine is named after the engineer Edward Bull and was built by Harvey & Co in Cornwall in 1856.  A Bull engine consists of a steam cylinder and piston inverted over a pump, which dispenses with the need for a giant rocking beam, as fitted to the other engines at Kew. This design meant that a Bull engine took up about half the space of a beam engine of similar pumping capacity.

The engine ran until 1944 when, along with the other engines at Kew it was, taken out of service.    The Bull Engine Restoration Project, which was launched in January 1999, was set up to restore the engine to working condition. Since then volunteers have worked tirelessly to restore the engine to full steaming condition, aided by generous grants from the Heritage Lottery Fund (£14,500) and the PRISM fund (£20,000) and many generous donations from private individuals.

Rust removal, scraping, painting, polishing, machining and heavy dismantling have challenged the volunteer team, to the extent that they began to wonder whether the project would ever end!  Many tons of mud and silt were shovelled up by hand from the damp and dark basement and a number of interesting items were found during the work, including old bottles and tools and even a set of false teeth inscribed with the name of a now long-dead boiler stoker!

Nick Morgan, Project Leader, said: "The Bull Engine is the largest of its type in existence and the only example remaining in its original location.  It is also, now, the only working Bull engine in the world.   The engine will now be demonstrated regularly and visitors will be able to witness the awe inspiring sight of this massive engine working just as it did during its long working life of over 80 years”.

This magnificent engine will be demonstrated for the first time to the public on Saturday 17 and Sunday 18 May between 2:15pm and 2:45pm each afternoon.  Thereafter, it will operate on all ‘Giants of Steam’ weekends as advertised throughout 2008.