Complex sentence: In 1852 the Leeds Northern Railway (LNR) had reached Stockton and formed a junction with the Clarence Railway Stockton branch; an alliance had been formed and in anticipation Hartlepool West Harbour had been enlarged from.
Split into simpler sentences: In 1852 the Leeds Northern Railway (LNR) had reached Stockton and formed a junction with the Clarence Railway Stockton branch. In anticipation Hartlepool West Harbour had been enlarged from.