Great Eastern Railway replaces Lynn and Dereham Railway
BTR (Bury St Edmunds and Thetford Railway) – became part of the GER in 1878.
EAR (East Anglian Railway) – taken over by ECR in 1852 but existed until the 1862 Act
ECR (Eastern Counties Railway) – was the principal constituent of the GER in the 1862 Act
EHSR - Ely, Haddenham and Sutton Railway - although independent, the GER had a third share of its capital.  The GER also provided staff, locomotives and rolling stock in return for 50% of the gross takings. Changed name to ESIR in 1878
ESIR - Ely and St Ives Railway - taken over by GER in 1898
E&NR - Ely and Newmarket Railway - built Ely to Newmarket line. Formed in 1875 and taken over by GER in 1898.
ENR - East Norfolk Railway - built many lines in East Norfolk - later vested into the GER
ESR - East Suffolk Railway - taken over by ECR in 1859
EUR - Eastern Union Railway - taken over by ECR in 1854 but existed until the 1862 Act.
FR -   Felixstowe Railway - line operated by GE from 1878 and taken over fully in 1885
IBR - Ipswich and Bury Railway - amalgamated with EUR in 1847
LBR - London and Blackwall Railway - leased by the GER in 1866, but remained independent until the 1923 Grouping.
LDR - Lynn and Dereham Railway - amalgamated with LER to form EAR in 1847
LER - Lynn and Ely Railway - amalgamated with LDR to form EAR in 1847
LHR - Lynn and Hunstanton Railway
LID - London and India Dock Railway Company - lines operated by GER from opening
LRH - Lowestoft Railway and Harbour Co - leased line to NR in 1847
N&ER - Northern and Eastern Railway - leased by the ECR in 1844, the N&ER lasted as a legal entity until 1902.
NEW - Newmarket Railway - purchased by the ECR in 1854 but existed until the 1862 Act
NR -   Norfolk Railway - formed when the N&BR and Y&NR merged in 1845 - worked by ECR from 1848 existed until the 1862 Act
N&BR - Norwich & Brandon Railway - merged with Y&NR in 1845 to become the Norfolk Railway
RSJR - Ramsey and Somersham Junction Railway - became part of the GNGEJR in 1897
STJR - Stratford and Thames Junction Railway -  part of the ECR
SAWR - Saffron Walden Railway - purchased by the GER in 1877
SVR - Stour Valley Railway - taken over by EUR in 1848
TEN - Tendring Hundred Railway - vested into the GER 1883
THJR - Tottenham and Hampstead Junction Railway
TSR - Thetford and Swaffham Railway
WHBR - Ware, Hadham and Buntingford Railway - merged with GER in 1868
WFR - Wells & Fakenham Railway
WVR - Waveney Valley Railway - taken over by GER in 1863
Y&NR - Yarmouth & Norwich Railway - amalgamated with Norwich & Brandon Railway into the Norfolk Railway 1845
succeeds supersedes substitutes takes over fills in for