There is a scathing review of a Doomwatch episode from Canada's Globe & Mail on July 5th 1971 referring to the broadcast of Tomorrow, the Rat on 2nd July 1971. It is interesting to note that the episode is referred to as The Day of the Rat.
Tries for adventure, Doomwatch just dull
By Kaspars Dzeguze
"Doomwatch must have struck some television executive as a portentous title for a vaguely scientific, allegedly adventurous series of hour-long shows which have their roots in that media-nurtured garden of weeds—ecology.
But to judge by Friday night's premiere offering, The Day of the Rat, there's little chance Doomwatch will tick off the minutes to ecological disaster, since this is clearly another in the series of wildly inaccurate forecasts of things to come.
It's hard to understand why a story revolving around the breeding and escape of intelligent, carnivorous rats (rattus sapiens, as one of the Doomwatch scientists whispers in a technical aside), with a preference for human flesh, who end up terrorizing London, should be so lethargic and un-inspired.
The show's staff could surely have cribbed enough ideas from the monster-creature films that abound to produce an hour crammed with effective second-hand ideas. But no—it seems pride demanded an original disaster unblemished by previous failures. And how original is the ecology angle now? Perhaps Doomwatch will demonstrate uniqueness in the subsequent weeks through the very depth of its fall."
With special thanks to John Corcelli and Anne at the CBC Reference Library for tracking down this news item for doomwatch.org