So everything had been working fine, and without you changing/adding/fiddling with anything whatsoever on that circuit the fuse started blowing whenever you turned the light on?
That's exactly right.
I noticed the switch was faulty
What was the fault, and how did you notice it?
I noticed the switch was faulty just after the fuse blew.
So, I may have reversed he wiring but can't work out if this could be causing the problem to continue
It can't - switches just make and break a connection between the two conductors, they work either way around.
Thought so.
I've checked the other wiring as far as possible and it seems fine.
How have you checked it?
Looked at it for loose connections and water.
Any info and advice is welcome.
Unless you have a multimeter and an understanding of how electrical circuits are wired you're going to struggle. Getting an electrician might be your best bet.
Thanks, you've confirmed my suspicions but I live in hope.