Complex sentence: In 1854, it was amalgamated into the North Eastern Railway (NER), which in the 1923 grouping of railway companies, became part of the London & North Eastern Railway (LNER).
Split into simpler sentences: In 1854, it was amalgamated into the North Eastern Railway (NER). In the 1923 grouping of railway companies, it became part of the London & North Eastern Railway (LNER).