The Daleks take control of London in the 1964
adventure “The Dalek Invasion Of Earth”
The TARDIS materialises in London sometime after the year 2164. Dalek invaders are now ruling the Earth with the aid of humans converted into zombie-like Robomen, but they are opposed by a group of resistance fighters led by the wheelchair-using Dortmun.
The travellers discover that the Daleks have established a huge mine in Bedfordshire, their aim being to remove the Earth's core using a huge bomb and replace it with a powerful drive system so that they can pilot the planet around the galaxy. Ian manages to create a barrier in the shaft in order to intercept the bomb. The resulting explosion destroys the Daleks and their mine and creates a huge volcanic eruption.
Susan has fallen in love with resistance fighter David Campbell, and the Doctor decides to leave her on Earth to find a new life with him, while he continues on his travels with Ian and Barbara.(http://www.bbc.co.uk/doctorwho/classic/episodeguide/dalekinvasion/detail.shtml)