The scale of the Crossrail project can be seen by footage captured by an aerial drone flying within the tunnels.

Crossrail is Europe’s biggest infrastructure project, with 73 miles of railway being built beneath London’s busy streets.

The tunnels are due to open in 2018, and remain a hive of activity as construction workers attempt to meet the target to connect Berkshire and Essex.

Crossrail’s health and safety chief’s finally agreed to give the BBC permission to film within the tunnels after months of negotiations.