5 inch broad gauge GWR 4-2-2 ''Iron Duke''

Rarest of the rare, this is only the second broad gauge locomotive we've ever bought, the first - a GWR Rover Class 4-2-2 "Bulkeley" in the same gauge - sold way back in 2003.

The model is the work of a highly capable engineer, a man responsible for building nine locomotives in a fifty year model making career that started before the war. He was a prolific contributor to "Model Engineer" magazine, writing learned articles on a diverse range of subjects including lathe improvements, model locomotive design, small locomotive performance, valve setting, thyristor control and valve gears amongst others.

The idea for "Iron Duke", his last locomotive, came about as a result of encouragement by fellow club members to build a 5 inch gauge locomotive, all preceding engines having been built to 3/4 inch scale for 3 1/2 inch gauge track. Concerned at the size and weight - the "manageability" as he put it - of a 5 inch gauge locomotive, a solution suggested itself in the form of a broad gauge model, in 5 inch gauge close to his preferred 3/4 inch scale.

Gooch's "Iron Duke" was picked as the prototype, a general arrangement being worked up from a commercially available outline drawing, with visits to the Great Western Museum at Swindon enabling study of parts from the contemporary "Lord of the Isles", along with the replica of "North Star" which provided details of motion and valve gear.

Completed almost fifty years ago, "Iron Duke" remained one of two models retained by the builder's family - the other a 3 1/2 inch gauge Midland 4-4-0 - both arriving at our workshop recently after many years on display.

In remarkable condition for its age, although at some stage in its life it has suffered minor accident damage, the back of the boiler taking a knock which dented the firebox cleading, bent the regulator stem and put a small kink in the backhead - we suspect that the blower handle and two handrail stanchions went missing at the same time. Happily it hasn't impaired the structure or integrity of the boiler - a recent twice working pressure hydraulic test was passed with flying colours.

The engine itself steams freely and runs beautifully in both directions, a credit to its builder. You may notice in the video the pressure gauge isn't working - not uncommon, we replace dozens of dead or inaccurate gauges a year on engines that pass through the works for servicing.

What stayed our hand in this case was the fact that the gauge was made by the builder himself - highly unusual, it's only Louis Raper's fabulous 14XX and the late Keith Massey's engines that I can bring to mind similarly equipped (and Keith found gauges so fiddly to make that he only had four, which were swapped between the several dozen engines he'd built as required!).