From the Radio Times:

5.40
DR. WHO
An adventure in space and time
starring
WILLIAM HARTNELL
WILLIAM RUSSELL
JACQUELINE HILL
and
CAROLE ANN FORD

The Waking Ally
by TERRY NATION
Fights arranged by Peter Diamond
Title music by RON GRAINER
with the BBC Radiophonic Workshop
Incidental music composed and
conducted by FRANCIS CHAGRIN
Story editor, David Whitaker
Designer, Spencer Chapman
Associate producer, Mervyn Pinfield
Producer, VERITY LAMBERT
† Directed by RICHARD MARTIN
The reason the Daleks are here is discovered.  The travellers prepare for the final battle.

Susan Forman leaves at the end of this serial.

This serial was made into a motion picture entitled Doctor Who and the Dalek Invasion of Earth 2150 A.D. starring Peter Cushing as the Doctor.