Summer (audio story)

 was a 2007 Big Finish Productions full-cast audio short story, featuring the fifth Doctor and Nyssa. It dealt with the problems that arose from the Doctor carrying anachronistic money around in his pockets during the time that Sir Isaac Newton was trying to catch counterfeiters in late 17th century England.

Publisher's summary
During the stifling heat of a summer past the Doctor and Nyssa suffer the vengeful wrath of Isaac Newton.

Cast

 * The Doctor - Peter Davison
 * Nyssa - Sarah Sutton
 * Guard - Jeremy James
 * Molly - Sunny Ormonde
 * Jailer - Trevor Littledale
 * Sir Isaac Newton - David Warner

Continuity

 * The Doctor expresses interest in visiting the Council of Nicaea one day, which he later does in BFA: The Council of Nicaea.
 * The Doctor quotes a few lyrics from Who is the Doctor.
 * While captured in a prison cell, the Doctor laments that he has not found the time to make a new sonic screwdriver since the original's destruction by the Terileptil leader in 1666. (DW: The Visitation) The Seventh Doctor would eventually make a replacement sonic screwdriver at some point prior to the events of DW: Doctor Who (1996).
 * The Sixth Doctor would later be imprisoned in the Tower of London in 1554. (BFA: The Marian Conspiracy)

Timeline
As with all fifth Doctor/Nyssa stories, this one broadly occurs between DW: Time-Flight and Arc of Infinity. More specific placement is fairly arbitrary. One possibility, amongst others, is that it happens after BFA: The Game and before ST: Greenaway.