With exclusive access to Crossrail Ltd and Transport for London, this final chapter of the series follows the race to fix the railway's high-tech software and systems to launch the new Elizabeth Line in time for the Queen's platinum jubilee.

We follow 83-year-old site manager Jim Forrest - one of the oldest engineers on the project. He joined the Whitechapel Station build in 2009 and has seen it from tunnel boring and concrete pouring to constructing the station steel works.