'Verdigris', written by Paul Magrs, features the Third Doctor and Jo.
Back Cover Blurb
Jo Grant had no inling of the ship that revolved in orbit like a discreet, preposterous though in the mind of someone serene but bonkers
High above London and its crust of smog, stretched tall above the soapy atmosphere of the Earth, is a ship the size and exact shape of St Pancras railway station.
On board, the Doctor and that mysterious lady adventurer, Iris Wildthyme, are bargaining for their lives with creatures determined to infiltrates the 1970s in the guise of characters from nineteenth century novels.
Without the help of UNIT, the Doctor and his friends face the daunting task of defeating aliens, marauding robot sheep, the mysterious Children of Destiny and… the being who calls himself Verdigris…