In reply to john spence:
Three Cliffs or Pobbles will probably be more appropriate for a four-year-old if you can get there - the easiest climbs are very slabby and user-friendly, as you know.
If you're actually in Porthcawl, you may as well give Box Bay a try. It's a lovely little crag and I really like it! The only thing is, on the main wall, the first two metres are actually a bit blank so he might struggle to get off the ground!
If he's happy about being lowered, you might actually get on better by lowering him halfway down some of the easiest routes and having him climb back up to you. Or have a look around - there are lots of smaller walls that might suit. It's all a bit steep and fingery but often young children excel on that sort of ground...
Post edited at 17:41