From the Radio Times:

5.50 Colour
Dr Who
The first part of a new adventure starring
Jon Pertwee
The Mutants
A six-part story
by BOB BAKER and DAVE MARTIN
Part 1
A mysterious summons from the Time Lords takes Jo and the Doctor straight into danger.

Title music by RON GRAINER
and the BBC RADIOPHONIC WORKSHOP
Incidental music by TRISTRAM CARY
Script editor TERRANCE DICKS
Designer JEREMY BEAR
Producer BARRY LETTS
Director CHRISTOPHER BARRY