Set contains running numbers B873393, B873729 and B873758 in BR Bauxite with TOPs numbering 

Prestwins were British Railways’ answer to a problem encountered in the earlier Presflo design; namely, that finer-grained powdered solids tended to pool up in the Presflos’ square corners, preventing them from being fully discharged. Embracing the power of curves, Prestwins employed twin silos that enabled substances such as lime, sand and soda ash to slip effortlessly earthwards when subjected to compressed air (using the same principle as their angular cousins). The dual containers also allowed for quicker unloading.

Prestwins were constructed by both Metro-Cammell and Gloucester RCW and entered service from 1960. The first 31 vehicles sported a 10ft 6in wheelbase while the final 100 were longer (with a 12ft wheelbase) but lower and had a larger capacity.

Ranging far and wide, notable Prestwin traffic flows included alumina from Burntisland to Welwyn Garden City, sand from Staffordshire to Port Sunlight (Merseyside) and soda ash from Northwich. Sodium tripolyphosphate (no, it doesn’t
have an easier name!) was another regular inhabitant of the twin tubs, and this was carried from the Cumbrian coast to both Merseyside and Essex. Prestwins were also trialled with a variety of other slippery solids, including china clay, slate powder and salt.

All Prestwins entered service in BR’s bauxite livery but had an extra paint layer that meant they stayed looking ‘bauxitey’ much longer than other vehicles, whose reddish hues quickly descended into faded grot. Some Prestwins were painted dark grey or black in their later years, with many soldiering on well into the 1980s.

• Die-cast chassis
  
• ‘Ultraflex’ vacuum pipes
  
• Brass bearings
  
• Easy conversion to EM/P4, with 26mm axle
  
• Axle-box variations
  
• Fine metal steps and handles
  
• Subtle variations in printed detail across each set of three wagons