This is attached to the support structure of the venerable preserved beam engine at this site - SK5219 : Loughborough Beam Engine
I've been reading around this one. According to the records of James Watt & Co, a 12 hp six column beam engine was supplied to Lambeth Waterworks in 1850 and the standard cylinder size was 20.5" x 36". The Waterworks of London by Colburn & Maw, 1867 (you'll need deep pockets for this) refers to a condensing beam engine by Boulton & Watt, 24" x 36" emptying filter beds by a centrifugal pump belt driven from the flywheel. My friend John Porter from Kew Bridge Steam Museum informed me that - The minutes of the Metropolitan Water Board for 6th May 1932 discuss what to do with an 1850 built beam engine by James Watt & Co which is "of historical value" but is now redundant. It was used for draining the filter beds at Surbiton. They wanted it put on view somewhere but the Science Museum said they had no space. The Museum of Science and Industry in Chicago said they would have it but the Board wanted to retain it in the UK. The Governors of Loughborough College said they would like it so the Board agreed it would go there.
I have no doubt that this is the same engine throughout and I am very pleased that the College and the University have seen fit to retain it and keep it in reasonable order. You will note that Colburn and Maw get the manufacturer wrong and the cylinder size is also different. The centrifugal pump driven off the flywheel is almost certainly a later iteration and the reciprocating pump driven off the beam was almost certainly the original.