The Tour, along with the Doctor Who fandom, notes the passing of William Russell (Enoch). It is quite reasonable to postulate that without William Russell, Doctor Who might today be regarded as another obscure but fascinating bit of early 60’s television kitsch. Not only was Russell one of the very first Doctor Who companions, but he was ostensibly the essential companion.
Essential to ground the plots and selling the practical. Essential to split up the narrative as well as handling the physical when required. Essential to saving scenes when Hartnell would fluff his lines in the era of live-to-tape television. And essential to being the hero-figure Doctor Who needed while William Hartnell was still evolving away from being an occasional anti-hero.
Yes, William Russell was that important. Noting that, Russell provided the bridge all the way back to the beginning in the ‘support group’ coda near the end of The Power of the Doctor in 2022.
Just short of his century, William Russell was always essential.