The Cromer Tunnel was built by the Norfolk and Suffolk Joint Railway

Norfolk and Suffolk Joint Railway

The Norfolk and Suffolk Joint Railway was a British joint railway company.The NSJR was owned by the Great Eastern Railway and the Midland and Great Northern Joint Railway and consisted of two distinct sections: a line between North Walsham and Cromer via Mundesley, and a coastal section running...

 to take their Cromer Beach to Mundesley line under the Great Eastern's

Great Eastern Railway

The Great Eastern Railway was a pre-grouping British railway company, whose main line linked London Liverpool Street to Norwich and which had other lines through East Anglia...

 Cromer High to Norwich

Norwich

Norwich is a city in England. It is the regional administrative centre and county town of Norfolk. During the 11th century, Norwich was the largest city in England after London, and one of the most important places in the kingdom...

 line. Both portals of the tunnels are open but undergrowth and modern housing in the area make access difficult.

It is the only remaining former railway tunnel in Norfolk

Norfolk

Norfolk is a low-lying county in the East of England. It has borders with Lincolnshire to the west, Cambridgeshire to the west and southwest and Suffolk to the south. Its northern and eastern boundaries are the North Sea coast and to the north-west the county is bordered by The Wash. The county...

, but the narrow gauge Bure Valley Railway

Bure Valley Railway

The Bure Valley Railway is a minimum gauge heritage railway in Norfolk, within The Broads National Park.The railway runs from Wroxham to Aylsham and is Norfolk's longest railway of less than standard gauge. It uses both steam and diesel locomotives. There are intermediate halts at Brampton,...

 crosses Aylsham Bypass by means of a newly constructed Aylsham Bypass Tunnel

Aylsham Bypass Tunnel

The Aylsham Bypass Tunnel is the only railway tunnel in Norfolk, England currently open to trains. It carries the narrow gauge Bure Valley Railway under the Aylsham Bypass...

which replaces the former level crossing.