The Leicester and Swannington Railway (L&SR) was the first steam railway in the English Midlands and only the fifth in the world at the time. It was built to bring coal from West Leicestershire collieries to Leicester, where there was great industrial demand for coal. The line opened in 1832 and included a tunnel over a mile in length, a record for being the longest steam railway tunnel in the world when the line was opened, and two rope-worked inclined planes; elsewhere it was locomotive-operated, and it carried passengers. The engineer for the railway was George Stephenson (“the Father of Railways”). His son, Robert Stephenson, raised much of the capital used to build the line.
Further information, including other features and feats of the railway, can be found at these places:
Swannington Heritage
Wikipedia

Leicester and Swannington Railway in 1833. The co-ordinates are found on a crossing along the bend between Desford and Merry Lees.
At the posted co-ordinates is an information panel, containing various bits of information: a telephone contact; the location name; the O.S Grid Reference; the track mileage.
The O.S Grid Reference on this panel can be written as follows:
SK abcdae
For more precision, this can be re-written as:
SK abcdd daedd
The location of the cache is at:
SK (a) (2xc) (e) (c) (c) (d) (a+(a-c)) (2xa) (a-c) (e-b)
To find the location of the container you need to work with O.S Grid References. This can be done in a number of ways:
- With an O.S map
- With the "OS Locate" or "OS Maps" apps.
- Various grid reference finder websites
Please do not park along the dirt track if you intend to cache&dash this one as it will block access to the people who use it.
Good luck!