I don't actually know anything about them, but the shape of the head makes me think late 1970s. This would make them contemporary with "The Return of the Saint" on TV starring Ian Ogilvy which ran on telly 1978-79 although there would have been many repeats.
The earlier TV series starring Roger Moore ran from 1962-69, but the club does not appear to me to be a 1960s design.
The Simon Templar novels were written over several decades. Author was Leslie Charteris.
I would like to see some more pics of the whole set. The 9-iron does look attractive to me.
I've seen the putter with the saint logo but never the irons.
Saint Andrew Golf Co was a long running club manufacturer, going back to the hickory days.
Date wise for these I guess it would have to be some time while the TV show was popular. As to value, very hard to say but not a great deal, I imagine fans of the TV show would be more interested in them than golfers.
Certainly an interesting set though!
I seem to remember that "Custom Built" was a model from St Andrew Golf.