Bingowings said:
I don't think so, I definitely remember it being separate to "The Plank" (which I watched religiously as a child. I used to say 'Oh! And the Cat! Quite a lot, much to my parents annoyance) It might not have had Peter Sellers in.
I remember the last scene of the film quite well. A man and his wife pull up to their recently built house in their car, but because the builders took such a long time to build the house they now have loads of children. They go into the house, realise that the house has been wired incorrectly and the film ends. I think the last shot is that of a light-bulb with water pouring out of it.