Milton Park GeoCache Series 

After our recently placed GeoCache Series at Great Western Park, Didcot, we decide to place a few more caches in other parts of Didcot and surrounding villages, or duing our trips to other towns and cities, in order to honour local heros, and to reflect our rich local history, stories and heritage. We hope you will enjoy these new caches and may also learn something new when you are caching, thank you!

All our placed caches can be viewed at this public bookmark list: https://coord.info/BMFEC4E

Milton Park #278 - Milton Park Disused Railway (Officially Known as REALLY SideTracked - Milton Park)

Source: Open Railway Map

The Milton Park disused railway infrastructure in Didcot primarily refers to (1) the historic freight rail sidings serving the business park and (2) the repurposed Backhill Tunnel, a formerly abandoned rail underpass transformed into a pedestrian and cycle path.

Additionally, the area is bounded by the active Great Western Main Line and the nearby Didcot to Upton Rail Trail, which follows a completely separate disused railway line just south of the town.

1. Key Railway Features at Milton Park

• Milton Freight Terminal Sidings: Originally built to support the massive World War military logistics hub known as the Milton Depot, these tracks diverge from a nearby railway junction west of Didcot Parkway station. While the physical tracks remain, they are largely out of regular use, overgrown, and disconnected in sections.

• The Backhill Tunnel: This disused brick underpass runs beneath the main London-Paddington railway embankment. After being closed to the public for several decades, it underwent a redevelopment project funded by the Oxfordshire Local Enterprise Partnership (OxLEP). It reopened as a lit pedestrian and cycle link connecting the A4130 directly into Milton Park.

Backhill Lane Tunnel - before and after

2. History

The history of the Milton Park disused railway infrastructure is deeply tied to the military logistics hub that transformed Didcot from a quiet, agricultural village into a major transport town. 

The railway lines and sidings that run through the area were born out of wartime necessity. They transitioned through the industrial era before ultimately being adapted into the modern tech community and public trail networks seen today. 

🏭 World War I and the Birth of Milton Depot (1916)

• Before 1914, Didcot was heavily reliant on farming. However, its strategically vital position at the junction of the Great Western Main Line (GWML) and lines to Oxford made it an ideal location for wartime supply hubs. 

• The Royal Flying Corps Influx: In 1910s, the Royal Flying Corps established a massive storage facility known as Milton Depot.

• The Rail Sidings: To handle millions of tons of military hardware, an extensive network of industrial railway sidings was constructed. These tracks split off from the main line at a nearby railway Junction and ran directly into the depot's vast warehouses. 

🛩️ World War II and the D-Day Prep (1939–1945)

During the Second World War, the site was expanded further by Army and RAF Ordnance units. It became one of the most critical logistical lifelines in the South East of England. 

• The Spitfire Supply Line: The depot functioned as a key component of the war effort, storing and supplying Spitfire parts, aircraft components, machinery, and uniforms.

• Intense Rail Traffic: The dedicated sidings inside the depot worked 24/7, routing freight through to major southern ports and airbases.

🚂 Post-War Demilitarisation and the Birth of Milton Park (1960s–1970s)

Following the end of World War II, the UK downsized its military presence, causing many sprawling rural depots to face decommissioning.

• Closure: The Ministry of Defence officially closed the Milton Depot in 1960s.

• Commercial Transition: Later the massive 600-acre military landscape was auctioned off. Part of the land was allocated for the construction of the Didcot Power Station, while the section containing the railway warehouses became the Milton Trading Estate (later rebranded as Milton Park). 

• Mothballing the Tracks: As commercial transport shifted heavily toward road haulage, the intricate inner web of rail lines fell into disuse. The tracks were gradually built over, leaving behind the single, overgrown branch siding that still skirts the park today. Only a few original military units from the depot era survive today.

About this Mystery cache:

The published coordinates are the original Milton Depot Sidings and used to have disused railway tracks. To find this cache you do not need to go there, but just need to do some research and visit the tunnel to find the answers for the following questions. The cache is not located at the published coordinates.

1. How much money (A.B million pounds) was spent to transform the closed Backhill Tunnel into a lit pedestrian and cycle path? And when did this new cycle path open? Let the year be 20CD. 

2. The Milton Depot Siding tracks split off from the main GWR line at a nearby railway Junction and ran directly into the depot's vast warehouses.  How many letters are there in this nearby junction's name? Let it be E. 

3. In which year did the Royal Flying Corps establish a massive storage facility known as Milton Depot? Let the last digit in the year be F. 

And this depot functioned as a key component of the war effort, storing and supplying parts for Spitfire during WWII. The number of letters in the main Spitfire part (in plural) supplied here is G. 

4. After WWII, the Ministry of Defence officially closed the Milton Depot.  The last digit in the year of closure is H. 

And in which year was the massive 600-acre military landscape auctioned off, that part of the land was allocated for the construction of the Didcot Power Station, while the section containing the railway warehouses became the Milton Trading Estate (later rebranded as Milton Park)? Let the year of auction be 19JK. 

5. Finally, please visit the Waypoint, which is the north end of the Backhill Lane Tunnel. Facing the south you will find a white sign painted on the left tunnel wall, which has 4 digits on it. The 4 digits are XXLM. 

And on your right you will find another plaque, which has a year on the top line. The year is XXPQ. 

The final coordinates are a short distance away at:

N51 ( B - A )  ( C * D ) . ( E - G )  ( H + K )  ( M - L )

W001 ( F - G )  ( J * K ) . ( P - H )  ( E - L )  ( B * Q )

You may check your calculations using the checker.

Please also note: 

To celebrate the 19th SideTracked Day (10 August 2026), we are placing this REALLY SideTracked cache at Milton Park.

Please bring your own pen, and open & close the cache lid carefully so the cache and log book can survive longer. You might need a tweezer to help retrieve the log paper.

Please also replace exactly as found due to obvious reason, and please be careful with the possible thorns, stinging nettles, and overhead tree branches! Long sleeves, trousers, and gloves are recommended.

You do not need to enter any private land.

Thank you and enjoy GeoCaching!

FTF: Congratulations to Lmw1980 for their FTF on 30 August 2026!

About SideTracked Caches

This cache belongs to the SideTracked series. It is not designed to take you to a magical place with a breath taking view. It's a distraction for the weary traveller, but anyone else can go and find it too. More Information can be found on the SideTracked Series website at www.sidetrackedseries.info https://www.sidetrackedseries.info