A reprise of my Facebook comment, Paul! :)Reading annuals (kindly donated by older relatives) whilst in hospital recovering from a head injury at the age of 5.
That book cover proof looks like the Doctor and an unknown individual are singing to one another. And the diddy Doctor running from the helicopter has grown a tail. The brilliant thing being, those could easily be scenes from one of the stories within. The Doctor transmuting into Time Cat, who can only fend off the villain by singing at him.