At the time this was just viewed as a gentle skit, with the chance to see a few old Doctors, who agreed to appear because of the charity aspect, when there was no chance of formally arranging for them to appear in the show even if it had been running then.
Within the bounds of their existing dispositions (Tom and Jon both being irretrievably dotty, and Peter having lost the peachy bloom of his youth) everyone played the show for real and even though they were only brief, there were some lovely performances from Louise Jameson and Lalla Ward, as well as the other supporting cast.
Outside of the context of the skit, this item has a wider cultural impact, as it brought together Doctor who at its most camp, with East Enders at it's most depressing and had the two realities created for the BBC interact in an absolutely serious manner. In many ways this was a Doctor Who episode rather than an East Enders one, although it fits equally well, or badly, into the continuity of each. East Enders is as much a work of fiction as Doctor Who, but represents television's vision of the ordinary, everyday, kitchen sink lives of its viewers the same viewers who would sit down to watch Doctor Who, so in some sense this is an example of how the BBC picture the Doctor walking out into the audience.
There had been an idea in the 1960s to have both the Beatles and the cast of Z-Cars turn up in Doctor Who and neither proposal quite worked. Here the mingling of East enders and Doctor Who was pulled off, and even though it was like fingers down a blackboard for fans at the time, it could prove to be a much more important cultural marker for media historians of the future.
As an adventure it just about held together and pressed forward to a conclusion, however for those fans who prefer to see plot holes, this is Doctor Who as Swiss Cheese.
