Crossrail 2 is a suspended proposal for a hybrid commuter rail and rapid transit route in South East England, running from nine stations in Surrey to three in Hertfordshire, providing a new North–South rail link across Greater London. It would connect the South West Main Line to the West Anglia Main Line, via Victoria and King's Cross St Pancras. The intent was to alleviate severe overcrowding that would otherwise occur on commuter rail routes into Central London. When first proposed, the hope was for construction to start around 2023, with the new line opening from the early 2030s. The project's cost has been estimated at £31.2 billion.

The West Anglia Main Line is one of the two main lines that operate out of Liverpool Street. It runs generally north through Cheshunt, Broxbourne, Harlow, Bishop's Stortford and Audley End to Cambridge, with branches between serving Stratford, Hertford and Stansted Airport. The line runs along the boundary between Hertfordshire and Essex for much of its length.