Significant contributions to the Whoniverse: The second Baker to take on the role of the Doctor bears little similarity to previous incarnations other than his surname. He was more brash and certainly more egotistical, and had the worst fashion sense of any to date. I can understand his portrayal being divisive at the time, yet by modern standards an attempt to shake things up a bit and being less predictable certainly had some merit.
A recurring character was introduced in a Sixth Doctor story in the form of a Time Lady, known as The Rani. To my recollection, this is the first non-companion Time Lady we have met in the series outside of the realms of Gallifrey. She forms the role of recurring villain who is out for herself, as ill at ease working with the Master just as she is ill at ease working with the Doctor. Her story will prove to intersect quite significantly with the Doctor’s at a later date.
As already alluded to, i think one of the most memorable elements of the sixth Doctor is his outfit, which was as brash and loud as the man was himself. This was not a Doctor accustomed to stealth. Fitting with this nature is the storyline that I feel dominate’s this Doctor’s tenure; Trial of a Time Lord. The Doctor’s actions past and present come under direct scrutiny by the Time Lords, with the Doctor’s exuberance proving potentially disastrous. It is interesting to note that prior to this story, there had been a number of season-long storylines. However, these stories had been loosely connected serials with an end of season pay-off. Trial of a Time Lordwas a full season story bearing only one title, though subsequently story titles have been added. It was a bold move which also led to another first… the Doctor meeting a future incarnation.
Significant contributions to the Whoniverse: It was during Davison’s time as The Doctor that the Doctor Who franchise hit its twentieth year. As such, it was in that specific year that he led the biggest gathering of Doctors to date. Unfortunately it was not genuinely a complete gathering, as Hartnell had passed away, and Baker did not wish to be a part of the adventure. Regardless, it was a great special that also featured both the Daleks and The Master.
Speaking of The Master, this brings me to the next most significant contributions in the Fifth Doctor era. Anthony Ainley became The Master at the end of Baker’s reign, but he truly became a recurring character again with Davison. Despite many times being defeated and supposedly finished, he just kept coming back, setting up the character again for his memorable appearances in the modern series of Who.
Perhaps most significant though, and something the Fifth Doctor is best known for, is the fact that he did not use a sonic screwdriver. In an early Davison episode, the screwdriver was destroyed by an enemy to prevent the Doctor’s escape. No effort was made to replace it, a conscious decision made by the writers to prevent giving the Doctor an easy option out of his various scrapes. This was so unique for The Doctor at the time, that in some respects, it eclipsed the fact the he was wearing a celery stick in his lapel.