The origin of this phrase isn't easily traced back to a specific source. However, its likely origins come from the association of "catch" with:
* Catching up: The phrase "to catch up" suggests the act of filling in each other on things that have happened since the last time you saw someone. "Having a catch" can be seen as a way of catching up with someone in a relaxed and informal setting.
* Playing catch: Playing catch with a ball is a casual and enjoyable activity that often involves conversation and laughter. This association with a light-hearted and social activity likely contributed to the phrase "having a catch" being used to describe casual socializing.
* Catching a break: "Having a catch" can also be seen as a way of taking a break from daily routines and responsibilities to enjoy some light-hearted conversation with a friend.
In conclusion, the phrase "to have a catch" is a casual and informal way of describing a conversation or interaction with someone. Its origin likely comes from the association of "catch" with the concepts of catching up, playing catch, and catching a break, all of which involve socializing in a relaxed and enjoyable way.