Who killed the ‘Strategic Steam Reserve’?

Thursday, April 1 2010

The eastern entrance to Box Tunnel. Photo ©Derek Hawkins.

(Click on image to see original on Geograph and for details of licensing.)

Thanks to Bourne’s lithographs, the western portal of Brunel’s Box Tunnel is well known, but the eastern portal is less so. The latter is decidedly less ornate. Brunel had gone over budget during the construction of the Great Western Railway and the directors were demanding economies. So not many people are familiar with the eastern portal or know that it also has a small side tunnel to the north which led into a underground quarry used by the railway contractor as a source of the fine Bath stone used to embellish many of the buildings and civil engineering structures along the line.

The area had been quarried for many centuries, leaving behind an enormous complex of galleries and tunnels where the stone had been removed. In both the first and second World Wars, the quarries were used to store ammunition. The complex was named the Central Ammunition Depot, Corsham. It encompassed the underground quarries at Ridge, Monkton Farleigh, Eastlays, Browns, as well as the Tunnel Quarry at Corsham. During WWII, the adjoining Spring Quarry was converted at enormous cost into a Ministry of Aircraft Production factory. While Ridge Quarry was used almost ‘as is’, the quarries at Tunnel, Monkton and Eastlays were comprehensively re-engineered. A major underpinning exercise allowed adits to be straightened and rectangular storage bays to be constructed. Air conditioning, electricity generation and sewerage systems were installed.

After de-commissioning in the 1960s, the complex was broken up, Eastlays was used as a bonded warehouse, Monkton became a museum, was then closed and trashed by scrap thieves, parts of Monkton Farleigh were leased to a security company. Part of and in later years a store for the Royal Navy was developed as one of the Hawthorn Central Government (War) Headquarters sites. Tunnel Quarry remained in MoD hands. Part became the Corsham Computer Centre and part is used by RAF Rudloe Manor.  The portion with the rail link to the ex GWR main line was used to store the strategic steam reserve – a means of hauling MOD trains in the period immediately after a nuclear attack.

Carefully selected BR standard and ex GWR locomotives locomotives were subject to heavy overhaul and were withdrawn shortly after running in their bearings. They were taken at night to Farleigh Down sidings by a special crew – half dozen BR drivers and firemen who had undergone security vetting and had signed the Official Secrets Act. From Farleigh Down they would be taken on to the underground storage sidings at Tunnel Quarry by Ministry of Defence (MOD) crews. Here the engines would be mothballed according a special process developed by MOD scientists. Boilers would be drained, then flushed with dry air and then filled with nitrogen to inhibit corrosion. All bright metal surfaces were smeared with a special lithium-based grease to inhibit corrosion. The humidity in the tunnel was carefully controlled by means of special air dryers fitted into the air conditioning systems.

The strategic steam reserve would probably have continued into the 21st century had it not been for the problem of training the next generation of MOD locomotive crews. With the closure of the Longmoor Military Railway in 1969 the MOD had lost its own in-house training facility. The MOD drew up a specification for a steam locomotive simulator similar to those used to train aircraft pilots. The project was originally budgeted at £15 million, but the USA DoD demanded that as this was a part of a strategic defence system it should be programmed in ADA. The new specification was put out to tender which was won by Praxis Systems of Bath with a bid of £25 million. The system was ready for delivery when the MOD discovered that whereas they had specified a driving simulator, they had forgotten about the work of the fireman. Praxis were asked to submit a supplementary estimate for the additional work required. At this stage the paper trail gets decidedly cold and after receiving a few midnight phone calls from the “If you know what’s good for yer mate… ” brigade we discretely dropped our enquiries.

The steam locomotives of the strategic steam reserve were very quietly cut up and with the evidenced disposed of and the remaining witnesses sworn to secrecy the MOD put about the story that the SSR is just an urban myth.



  1. Strategic Steam Reserve, a load of cr*p. All bar 2 9F’s have confirmed scrapping sites, except those removed from Barry Island for preservation. Even 8F’s and ex GWR loco’s the gaps in the scrapping records are very small. As for loco crews being send home and ‘their’ locos disappearing. Well I can confirm that did happen of sorts. At Salisbury which was a staging shed for Southern locos being dispatched to the breakers in South Wales, frequentley those rosters were cancelled because very often the locos being towed had run hot and I can personally vouch for being collared into assisting the fitters dismantle motion or more than often the offending parts were freed with the oyy-acetylene burner. The next crews on then got those turns. Sorry starry eyed enthusiasts there never was a Stategic Steam Reserve – unless you look around the country TODAY to see c300 steam locos that might be used if the balloon went up.
    Now as far as a Strategic Reserve of Diesel locos, it is reported in Hansard that in response to a specific question that at that time there WAS a reserve of Diesel locos. Still then, mid 1980’s, there were still a few hundred Diesel locos, but today ..!!!

  2. They would never have had ex GWR locos in it anyway even if it did exist. Loading gauge restrictions barred them from virtually all other regions lines.

  3. Please check the date this was posted!!

    If there is/was a strategic reserve would somebody kindly provide the evidence. Sorry, but hearsay doesn’t count.

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