the great northern railway (gnr) was a british railway company established in 1846. the main line ran from london king's cross station via hitchin, peterborough, and grantham, to york. there was a loop line from peterborough to bawtry (south of doncaster) via boston and lincoln. there were also branch lines to sheffield and wakefield. on 1 january 1923 the company became a part of the london and north eastern railway. today, the gnr main line forms part of the east coast main line.