By Keith Bucklitch


“Isibutu” was built by Messrs. Bagnalls of Stafford as one of a batch of ten locos built for the Tongaat Sugar Co, of Natal, South Africa in 1929.  Latterly she was transferred to the Sezela Sugar Estate in Natal where for a period she (he) bore the name “Robert Armstrong”. The loco has since been returned to the United Kingdom and latterly has been travelling round the country, appearing at a number of live steam railways.  When I first saw the loco, she was sitting in the narrow gauge shed alongside the GWRy at Toddington, Gloucestershire where I was subsequently able to climb all over her to take both measurements and photographs.

Robert Armstrong
Photograph of ‘Isibutu’ when named ‘Robert Armstrong’ in Natal
by kind permission of Paul Catchpole,
Locomotives International

Isibutu GA Drawing

'Isibutu' at Statfold Barn
‘Isibutu’ as running today on the Statfold Barn Railway
by kind permission of Tim Edmonds, Marlow & District Railway Society

“Isibutu” was built purely for the two-foot gauge and has mainframes that are only some 32″ apart.  However to appeal to a larger number of modellers, I have used modellers license to increase the frame spacing to accept 45mm gauge wheelsets.  The driving wheels can be adjusted on the axle for different gauge, but it will be necessary to change the bogie truck entirely in order to change gauge.

Steam test

I also wished to design the locomotive so that as far as possible it could be constructed with the use of hand tools, and the purchase of suitable commercially available components.  I had a pair of Roundhouse cylinders to hand, so using these, with the wider frame spacing, the overall width of the loco is 4mm (3″) overscale.  I then sought out other commercial components to use in the model.  Therefore, a potential builder can purchase the following items.  (Names in italics are possible sources of components.) It is probable that this is not a complete list of either components available or suppliers.

  • Cylinders – Roundhouse
  • Valve Gear  – Roundhouse
  • Smokebox – Roundhouse, ‘Billy’
  • Boiler – Finescale Engineering (Tony Sant)
  • Safety Valve, boiler filler, dome – Roundhouse
  • Steam manifold, banjo fittings, regulator, pressure gauge and siphon – Roundhouse
  • Lubricator, gas tank, gas burner – Roundhouse
  • Gas control valve – PPS Steam Models, Roundhouse
  • Wheels, axles, bushes, cranks & crankpins. – Essel Engineering, Finescale, Roundhouse
  • Sprung buffers. – Brandbright, Essel Engineering
  • Handrail knobs – Blackgates Engineering, MES etc.  (Use 2 1/2″ / 3 1/2″ gauge items.)

Isibutu early run

My construction series for “Isibutu” will commence in the May 2009 Association SMT Magazine where a complete set of drawings will be available. It will be necessary for the builder to make the following components: –  Main frames, buffer beams, cab, side tanks, bunker and small details.  If there is sufficient interest, I can probably obtain sets of frames, modified valve gear rods etc laser cut.  A set of etched brass components for the superstructure may also be made available.


Keith Bucklitch