Childrens TV program late 70s / early 80s

This is a bit of a long shot arising from a faint shared memory of my wife & I.

We both marginally recall a TV program where the main character, a young boy, used to talk to himself saying something along the lines of "mmmm....yes....sectret....yes... me.... malcolm.....secret"

Yes I know - pretty obscure. And not even sure about the name Malcolm! It comes from somewhere buried deep in our childhood memories and has been driving us mad trying to dredge up the name of the show! Can anybody put us out of our misery and enlighten us?

I can’t say it rings any bells with me. Can you remember anything else about the programme at all? Was it British? Was it shown at tea-time (“part of children’s hour”) or the weekend?

Yes definitely British and tea time kids TV. It was a short-lived series. Late 70s/ early 80s. I think a serious program rather than comedy / light entertainment ( but not certain of that). Either BBC or ITV.

I remember a friend used to mimic the character’s line when we were kids and when it came up in conversation with my wife recently it rang a distant bell which made us curious for more information.