The Doctor's whistle was a tool found inside the Memory Tardis. Whose and What memory the Doctor's Whistle is from is unknown.
The Doctor's whistle appeared as a steel whistle on a red lanyard. The lanyard is the same color as the molecular rope. The Doctor's whistle has the ability to control the Tardis to an unknown extent. (TV: Empire of Death [+]Loading...["Empire of Death (TV story)"])