After 2 deliverys today my modified gate is still standing. So cementing was the way to go. I noticed it still had a problem. When it swung shut it bounced back open. The catch didnt catch every time. I pplayed about with it for a while opening and shutting it. It took a while to see the problem. The post being concreted in has made the post vibrate when slammed. It tried to latch but was just bouncing out again. After a few atempts at making it solid. I solved it by cutting and screwing a small block between it and my metal arch.
Ive been out opening and shutting the gate so many times today Ive lost count. I doesnt bounce anymore and just quietly clunks and latches. I think its sorted now. But time will tell.