Images have been released of Piccadilly line trains under construction at a factory in Goole, East Yorkshire.
It comes ahead of the official opening of the factory by Secretary of State for Transport Louise Haigh and Mayor of London Sadiq Khan.
Work on assembling the first 10 trains for London Underground began in March. They are expected to be in service from 2025.
The new trains, which will be fully air-conditioned and more accessible, are expected to increase passenger capacity on the Piccadilly line.
Khan said: “This train manufacturing facility in Goole is a fantastic example of the expertise we don’t have and how investment in London benefits the whole country.
I’m excited to continue working together with the new government to build a better, fairer and more prosperous London, and country, for everyone.”
Tom Edwards, BBC London transport correspondent:
The mayor’s message is investment in London is investment in the UK.
This investment, started by the former Conservative government, will provide 700 jobs in Goole, but will Sadiq Khan get more investment from a new Labour government?
He has grand plans for a DLR extension to Thamesmead and a Bakerloo line extension but they will need significant investment.
At some stage central government will have to say no.
These trains for commuters will offer a big improvement for the Piccadilly line with air conditioning and walk-through carriages.
Crucially, there will be more of them so they can increase capacity in peak hours.