How are points calculated in a 9 hole comp?

I suspect it wasn't a proper 9-hole qualifier which would need a 9-hole SSS authorised by England Golf. That SSS has to be used in conjunction with a conversion chart which gives a 9-hole handicap based on your exact handicap. From my experience, that will be less than half of your playing handicap. I may be wrong but I think your club may have thought it OK just to use the 18-hole SSS and half the playing handicap. In that case it couldn't be a qualifier.

Oh, and as far as I remember, Cat 1 players cannot play in 9-hole qualifiers.