* It was British, I'm fairly sure
* the end titles always showed an aerial shot of a lighthouse.
* it was sci-fi, I think - there was a bad guy who wanted to rules everything, who had various chemical & psychological means to do so
* I think the protagonists were children, but I can't remember anything about them.
* in one episode, a train carriage full of soldiers was filled with a strange gas: the soldiers all got up and left the carriage as though they were obeying unspoken comnmands.
Does anyone else remember a series like this?
Remembered the show, finally - it was Freewheelers