Martin Mill military railway

The northernmost of the two lines laid by the military served the guns named "Winnie" and "Pooh", which were 14" naval gun emplacements capable of hitting targets on the other side of the channel, mainly the German guns on the French coast aimed at Britain. Winnie was the first UK gun to land a shell on mainland Europe in August 1940 in reply to the German long range guns that started bombarding Dover on the evening of 22 August.^[5] The sister gun, Pooh, was active from March 1941. This branch of the railway also had some firing spurs for the use of rail mounted guns (see below). There was also a branch off this line to another battery near the RAF Camp.

The southernmost of the two military lines served the guns "Clem" and "Jane" (the Wanstone Battery), which were active from August 1942, and the railway extended beyond them to the location of the experimental hypersonic gun "Bruce" (which was never used in combat), which was near the Dover Patrol Monument. At each of the guns the line ran behind the guns to supply munitions and cordite, and there was a line immediately in front of the guns to allow barrel changes. This southernmost branch also had firing spurs for the large rail mounted guns.

The rail mounted guns were large relics from WW1 (see BL 14-inch railway gun). During WW1 they had 14 inch barrels, an obsolete type scrapped in 1926, but the rail carriages and mounts were kept in storage between the wars. In 1939, the stored gun carriages were refurbished and then fitted with 13.5" naval surplus barrels. The rail carriages bore the original WW1 names of Gladiator and Scene-Shifter when discovered, from the accounts of Major Cleeve, who was tasked by Churchill with the organisation of heavy home defence artillery. A third gun, Piece-Maker, is not named in his account of the discovery of the guns in storage at RAOC Chilwell, but is also most likely a WW1 name. It seems the three rail guns on the Martin Mill Military Railway were kept under cover in either the Southern Railway's Guston or Lydden railway tunnels.^[6] The guns required very strong track and substantial ground anchors when fired due to the power of the recoil, and they had limited traverse, so they were fired from specially made curved railway spurs. The position on the curved track dictated the firing direction. In 1941 two of these guns were moved into position to fire on Calais 22 miles away and one gun jumped back 6 feet with the recoil and repositioning took some time, so firm anchoring was essential for a decent firing rate.^[6] Other smaller rail guns of similar vintage (9.2" guns and 12" howitzers) were deployed inland on rural railways to shell British beaches in the event of a seaborne invasion so were only used during exercises (with one exception, where a 9.2" rail gun at Folkestone West was used to fire at E-boats in the Channel, and in doing so de-railed itself).,^[6] but the rail guns on the Martin Mill military railway were larger and played an active role as part of the coastal battery.

The fixed gun emplacements were heavily camouflaged, and dummy gun emplacements were less well camouflaged. On the other side of the channel, the German large guns were instead built into massively strong fortifications.

The line was entirely worked by diesel-electric shunting locomotives requisitioned from the LMS (London, Midland and Scottish Railway) and SR (Southern Railway), three from the SR and six from the LMS. This was relatively new technology for the mainline railways, but the smoke from a steam locomotive on the cliffs would have been visible and could have given the guns' positions away to the batteries on the other side of the channel.

The three Southern Railway locomotives were the three experimental diesel-electric shunters delivered in late 1937, which had been on trial at Norwood Marshalling Yard. These had English Electric diesel engines and traction motors. They were requisitioned early in the war, and were released back to the Southern Railway in 1945. Under British Rail in 1948 they were designated as Class D3/12.

The War Department requisitioned many diesel shunting locomotives from the LMS in 1940. The details of the LMS locos used on the Martin Mill Railway are unclear, but it is on record that LMS 7063 failed in Guston Tunnel and had to be recovered.^[7] As the tunnel was a refuge for the rail guns, it is possible it was operating on the Military Railway. This loco was made by Armstrong-Whitworth and had an Armstrong-Sulzer 6LTD22 diesel engine. All ten locomotives of this class were requisitioned in 1940–1941. More likely to be used were the LMS locos 7069-7078 built by Hawthorne Leslie to English Electric design (later designated British Rail Class D3/6) - these were very similar to the 3 Southern Railway locos - and 7 of the 10 locomotives built were requisitioned by the War Department. Also likely candidates are LMS 7100–7109, also with English Electric engines (later designated British Rail Class D3/7). These were loaned to the War Department in 1941, and sold to them the following year.

Whilst working on the military railway the locomotives were stabled at the shed in Martin Mill railway station Yard.