Hello from mid-Wales

[rick]

They don't like squeezing through holes generally (very uncomfortable with feathers if you get in a panic and try to reverse) 4" is a bit big but they wouldn’t easily fit through a 4" hole (a bantam might, at ground level, but they would want to put their feet on or through the wire - they don't do wriggling head first!). You could put some smaller mesh in a strip over the bottom 12" or so.
Flying over is more likely to be the trick and they will use branches and coop tops as stepping points.

It sounds wonderful there! Better keep the location a secret or you may have us all turning up with our hens for a holiday

Actually, I've measured the gap mine will squeeze through at the end of the internal partition if I don't block it and its 4 1/2" but that is without any height restriction and they wouldn't attempt it without their feet on the ground and able to step through.

[ColinB]

Thanks Rick. I'll be off to the builders' merchants tomorrow and get some suitable small-mesh fencing.

It's rather nice round here after 30 years of living in the South=East. Our house is somewhere in the middle of all this - we still can't believe we live here: