18 February 2024
Steve Howard constructs a new 16mm exhibition layout, with a difference.

After 5 years and some 30+ exhibitions, it was time to think about a replacement for my ‘G’ scale, 45mm gauge, Hambleden Valley layout. I couldn’t just make another along similar lines, it had to be very different. The only criticism I had heard about Hambleden was that it was too big to run indoors at home, but also could not be left outside in the garden, so it was neither really an indoor layout, nor a garden railway. Hambleden was fairly unique in using radio controlled live steam locos on an end-to-end layout involving lots of shunting of rolling stock. So, this time I thought it had to be a ‘round and round’. However, it also had to be different from the usual offerings of unballasted track, a nod to scenery and out of the box rolling stock.

The new layout, called Pen-Y-Bont, was going to be 16mm scale on 32mm gauge track, and be based in Welsh slate territory. However, the unique feature this time was going to be that all the scenery was going to be from real plants, growing in soil and it would be left outside all year, except, that is, when dismantled and transported to exhibitions.

Due to the design brief of being outside all year, no wood could be used in the main baseboard construction. So, like Hambleden, the starting point was polycarbonate roofing sheets. To these were bolted 2-inch deep plastic plant trays fitted in turn with 2-inch expanded foam (Celotex or similar) insulation sheets painted matt black, to be used as a base for the track and helping to keep the total weight down as much as possible.

From the outset, this was designed to be a portable exhibition layout. The scenic section consists of five baseboards, each 4ft long x 3ft wide. Each has a 4ft x 2ft plant tray bolted to it. A secondary plant tray 4ft x 1ft containing the conifers and with a 14in high backboard made from plastic window fascia boards rests on the polycarbonate behind the main tray. This secondary board is not fixed and can be lifted off for ease of transportation. Rather than trying to make integral legs which would probably have to have been made of wood, or using the Hambleden system of 3 inch x 2 inch beams on trestles, I opted to use portable tables with plastic tops and metal fold down legs.

I am intending to use the Hambleden LED lighting strips above the layout as I know some exhibition halls can be quite gloomy and lighting the layout makes a big difference.

The main scenic boards when finished with track, plants and soil, weigh around 20kg, depending on how wet or dry the soil is. They are a two-man lift more because of their size and the need to keep them horizontal, rather than their weight. The separate back scenic boards with dwarf conifer trees are quite manageable single-handed.

A drainage hole was made at the end of each board and was fitted with a coil of copper wire and surrounded with horticultural grit. The layout is normally kept on a slight incline to drain the boards during periods of heavy rain.  This hole can be plugged if required to stop water dripping onto the floor of an exhibition venue.

The trays were filled with a piece of insulating foam. Once the track plan was decided upon, this foam was cut around the track to form the planting pockets. The cut edges of the insulation were sealed with black paint. The seed trays with the conifers you may have seen in early photos, were later removed and the trees planted directly in the long plant trays.

For the non-scenic return loop and a fiddle yard - in the garden these are part of a garden line, but for exhibitions, portable boards were lightly constructed from 12mm MDF. There are five 4ft x 2ft boards. However, the middle one is made of two layers of 6mm MDF. The bottom board connects to the two adjacent ones, but the top layer has a rectangular cut-out in it to accommodate six interchangeable cassette trays to hold the stock. These cassettes are 5” wide and a metre long with a 6mm MDF base, to hold the six train consists, three for each direction and can be aligned to the feed tracks each side.

These five MDF boards currently rest on the Hambleden trestles, but I may change this to more portable tables. The MDF is supported on two longitudinal pieces of twin slot shelving support bolted to the MDF and there is no other timber framing. The scenic and non-scenic sections are linked with two 2ft x 1ft x 1/2in MDF boards that rest on the plant tray one end and the MDF baseboard the other.
All these boards are painted with matt black emulsion paint on both sides and edges. There are locating pegs in the end of the metal framing to locate and align the boards.

The track is Peco SM32 to represent 2ft gauge. Most is set-track, save the front loop and some in the fiddle yard. The track plan is basically a single line through the station with an outer passing loop. There is a small head-shunt at either end of the station, only really used to display stock.

As the model is set in Welsh slate territory, I used slate for ballast. I made my own from a bag of slate chippings from the local garden centre. Pieces of slate were crushed with a club hammer and then sieved to remove the larger pieces. It took many days of slate bashing to provide the required quantity for the layout.

The slate was mixed 50/50 with sieved compost and was first laid dry and brushed into place. It was then lightly sprayed with water before dribbling on a 50/50 exterior grade PVA and water mix. It has consolidated over time and shows no sign of washing away despite of lot of rain at times.

The rail sides and chairs are painted a rusty colour and the track has naturally weathered outside in the garden. Track power is not used so electrical continuity is not a problem. For the rail joints across baseboard joins, sliding fishplates are used to align the tracks. To make the process easier, small pieces of bent wire are soldered to the bottom of the fishplate so that they can easily be gripped with a pair of pliers.

The Peco points have had the centring spring removed and are lightly biased in one direction allowing trains in one direction through the platform and via the passing loop in the other.

Over time, the track bed is being slowly consumed by the vegetation to remove the pristine mainline track appearance to something more akin to a neglected poorly maintained narrow-gauge line.

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Regular trackside maintenance is required to clear excessive vegetation and to keep the rails clear to avoid derailments.  The heat from the live steamers with the hot cylinders does quite a good job of this, but small pruning shears are an essential in the tool kit.

There are not many lineside features or buildings on the layout. The main feature is the station building, a Pendle Valley resin kit. The platform is a piece of polycarbonate sheet and edged with real slates. The wall at the back is again made from pieces of real slate stuck together with waterproof PVA. The slates are available in packs from Stacey’s Miniature Masonry, intended for the doll’s house market, but eminently suitable for 16mm models as well.

None of the Hambleden stock (apart from the Roundhouse locos) is suitable for re-gauging so I had a lot of new stock to build, currently an on-going process. However, train consists are limited to one metre in length because of the cassette system in use.
Apart from the five Roundhouse live steam locos, there are a couple of R/C battery locos. A Slater’s etched brass kit of a Quarry Hunslet and a GRS Peckett saddle tank. By the time you get to see this layout, there may be more!

A minimum of six train consists are required, three in each direction. These consist of the following:

  • Quarryman’s coaches
  • Various Passenger coaches
  • Various Passenger coaches


  • Slate wagons
  • Goods wagons
  • Goods wagons or p-way train

There are some static display wagons built for fun and heavily rusted, these are normally left in the head-shunts and include Slater’s skip and slab wagons and some Hudson tippers from Slater’s and Binnie.

I just love rusting stuff with iron powder. Large quantities of this can be bought cheaply on-line. I first spray the article with 3M Photo Mount. Then using a large soft make-up blusher brush, I lightly dust the surface with iron powder and leave to set.  Depending on the final rust colour I apply an acidic wash. For an orangey colour I use copper sulphate solution, again large quantities can be purchased cheaply on-line. For a darker colour I use other acids such as soldering flux or Carrs Metal Black.  I find other suggested liquids such as vinegar or lemon juice to be too weak.  Once dry, they all benefit from being left outside in the garden in all weathers for a few weeks (or permanently).

Other wagons for running in train consists include a couple of WD vehicles. There are currently a number of other on-going projects on the workbench at present to increase the stock levels. These includes some coaching stock, a gunpowder wagon, a couple of open wagons and a box van or two.

Operation is basically continuous running around the circuit, but with stops at the station and a possible drop off and pick-up of a wagon or two. Not as interesting perhaps as Hambleden, but the live steam locos still have Slomos fitted, so no high-speed trains. There are also currently a couple of R/C battery locos just to give the steamers and the operators a break in what is otherwise a quite intensive service. The six train formations are stored in cassettes and simply moved in-line with the running track when required.

The layout comes apart easily, there are no inter-board connectors, it just relies on the weight and the boards are aligned by eye. The boards slide into the Hambleden rack in my transit van.  I hope to attend a number of exhibitions in the coming months so hopefully you will get to see it for yourself.

The layout is constantly changing each year as plants grow and spread (or die) and each season changes the flowers and the colour of some of the leaves. On damp days in the Autumn, the mosses flourish and in hot dry summer periods the Thymes are a profusion of colours. The layout survives well being kept outdoors in the garden all year and the alpines have proved very hardy.

The two biggest problems are watering and birds. I need to keep some of it covered with netting to stop the birds pulling up the moss looking for grubs. The soil is very free draining so excessive rain has not been a problem, but it will dry out in hot sunshine and needs careful monitoring. In very dry weather it needs a regular soaking from a hosepipe or several watering cans, but at other times an occasional light spray is all that is required to keep the moss and the Soleirolia happy.

Has the project been a success? I think so. Although this is a portable layout, I think it demonstrates that you can have a garden railway with a high degree of realistic scenery using real plants. It’s also possible to make it portable.

Although largely complete now and ready to exhibit, most layouts are never really finished as there are always more details to add, things to change etc. Even more so with this, like a garden, there is always stuff to attend to in the planting, pruning, dead-heading etc.