Sixth Doctor's blue coat

The Sixth Doctor in his blue coat. (WC: Real Time)

Later in his life, the Sixth Doctor replaced his multicoloured coat with a blue coat, which functioned as a mourning suit. (WC: Real Time, et al.)

Ultimately, he began wearing the multicoloured one again towards the end of his life (TV: Time and the Rani) for the benefit of an amnesiac version of Melanie Bush, who preferred his original attire. When reflecting on his blue coat, Mel used "understated", "sombre", and "boring" as words not often associated with the Sixth Doctor. (AUDIO: The Wrong Doctors)