From Graces Guide
The Disley Tunnel was built by the Midland Railway in 1902 on its line between New Mills South Junction and Manchester Central, which was more direct than the congested and difficult lines through Stockport Tiviot Dale.
It was the most expensive work on the line and at 2 miles, 346 yards (3,535 m), the second longest tunnel on the Midland system.
By means of a connection on to the old LNWR line from Buxton at Hazel Grove that was opened in 1986, it is now part of the Hope Valley Line into the present-day Stockport railway station.
There is also a short (174 yard) Disley Tunnel nearby on the Buxton Line.
The tunnel runs under High Lane and Disley. The New Mills and Heaton Mersey Railway line goes underground where the Middlewood Way (the old Macclesfield, Bollington and Marple Railway), crosses the line, about 1/4 mile north of the A6 in High Lane. The tunnel passes under a housing estate, the Macclesfield Canal, Disley golf course and finally the Peak Forest Canal, just before emerging at Disley, meeting the Buxton to Stockport line.
The construction method used was to drive the tunnel bore from both ends, while also sinking 11 shafts from the top of the hill along the path of the railway. Work began in 1900, and the miners worked both directions from each shaft, which allowed 24 simultaneous working faces. Ten of the shafts were later used for ventilation, and are still in use - they are visible as large blue brick towers following the line of the tunnel.
The Midland Railway purchased the land above the tunnel in order to sink the shafts - boundary markers made of old rails, with the initials "M.R.", remain along the line of the tunnel.
A surface standard gauge contractors line was set up, using steam locos and a "steam navvy", following the subterranean path of the tunnel.
The construction of the tunnel brought a small army of navvies into the area. They were housed in temporary villages at New Mills and Wybersley, and in specially-built houses near the Rising Sun pub in Hazel Grove, which still exist, and are known as the "Navvy Mansions".
A church made of tin was erected at Wybersley, where the Midland Railway had a local administration office. Three hundred of the navvies' children attended the local schools.
The first section of the line opened in 1901 from Heaton Mersey to Cheadle Heath where a large station was built to serve Stockport. The second section from Cheadle Heath to New Mills South Junction opened to passenger traffic on July 1st 1902.
A local passenger station at Hazel Grove (South) was constructed, but this closed in 1917 as the main purpose of the line was express trains.
Sources of Information
-  Wikipedia