In this episode the team start the new series with an epic trip to discover how enamel signs are made, with exclusive access behind the scenes at AJ Wells’ factory on the Isle of Wight. We see all aspects of fabrication, try our hand at screen printing and follow the creation of a roundel and new signage for the renaming of Overground lines.

In the first of a bumper two-parter episode, the team hitch a ride on a battery locomotive as it weaves its way across the network deep into the night, learning about the specialist kit it carries to perform a challenging but rewarding job. Chris Nix, Laura Hilton Brown and Alex Grundon meet the crew who drive and coordinate these rarely spotted vehicles, and the team gets an exclusive front-seat view of a stretch of London’s Underground that you won’t see on any regular commute.

Last week saw the team hitch a ride on a battery locomotive as it weaved its way across the network. In the follow-up finale, Chris Nix, Laura Hilton Brown and Alex Grundon explore some of the areas you’ll never get to see on your commute – the engineering tunnels, secret passages and ancient equipment that make up the King’s Cross and Euston loops.

This week, Alex and Chris get to investigate one of the lesser-spotted engineering vehicles on the network - the rail adhesion train or RAT. These workhorses are actually former passenger trains that have been adapted and given a new life. But what kinds of equipment do they contain that allows them to perform this vital role across the network?