Can you name this show?

I was talking to my brother today as he was telling me about a TV show he used to watch and couldn't remember the name of it. I don't suppose anyone could help identify it? This is what he's described it as...

An old kids show about a group of kids who hung out in an old club house. In at least one of the episodes/series' there was a lead character called Simon. In the last ever episode, Simon returned after a long absence from the show to save the other kids from trouble. It ended with him walking off into the distance.

It's vague but if anyone can help, it'd be hugely appreciated.

CBBC? CITV? Maybe even a Nick show/airing? Rough sort of era? Could it have been an imported programme maybe?

He reckons it was CBBC, late 80s maybe.

Could it have been Simon and the Witch? That was on CBBC in the late 80s.

I ran that by him but he said it wasn't it. He said Simon wasn't a main character as such but he was, at some point, the leader of whatever group used to go this club house.

I've also asked if he thinks it was imported but he reckons it was a homegrown CBBC show.