Ok, I found some more photos from this sketch and I feel pretty comfortable saying it’s probably “The Psychiatrist” from the 1966 series of Not Only… But Also… It’s sad that these photos are the closest we’ll ever get to seeing this sketch. At least we can listen to it!
Here’s some interesting background on the topic they are satirizing in the sketch (from the blog Mind Hacks by vaughnbell)
It’s actually a parody of a technique in psychotherapy called “unconditional positive regard” in which the therapist accepts the person’s behaviour, experiences and emotions, good or bad, without judging the person’s core value as a human being.
This was originally developed by psychologist Carl Rogers as part of a humanistic or person-centred approach to psychotherapy.
It’s unsurprising that Peter would choose to write a sketch poking fun at psychotherapy, something which Dudley was heavily involved with and which Peter never put much stock in.