It's not a critique - yes, Colin Baker is a larger-framed man, and I see nothing wrong with that. I'm just saying that while he was the Doctor he DID noticeably put on weight, and not just let his hair grow out. From his first and last stories:
http://www.shillpages.com/dw/bakerc08.jpg
They did make a new waistcoat for him between the seasons to accomodate him, and a further one in the "future" story Terror of the Vervoids, where we was deliberately playing an older, heavier Doctor.
Davison's costume coat was not altered for "Time Crash". However, the pants were a paid that had been altered for Baker, being cut and expanded down the backside where we couldn't have seen it. You can see it in the Making of Time Crash, I think. The cricket vest and shirt underneath were new to fit Peter's current shape, though.
Mark