It apparently takes place sometime in the 21st century, and the end of a period during which mankind has abandoned space travel. London-based Galactic Salvage and Insurance goes bankrupt and is liquidated. Nightmare of Eden. The 7th Doctor and Mel visit the resedential complex of Paradise Towers. The Doctor and Mel help to unite the different groups and to defeat Kroagnon, the architect of the Towers, who is attempting to kill off all the inhabitants.
Placement here is somewhat conjectural.
However, it cannot be to long after, judging by the age of the Kangs. 2116 Professor Tryst's zoological expedition is on the planet Eden. The expedition includes Tryst's assistant Della, and Stott, with whom she is in love. Unknown to the others, Stott is in the Intelligence Section of the Space Corps, tracking drug-smugglers. Tryst, in reality the smuggler, shoots Stott, leaving him for dead.