One of Lotty's gate pins broke off. As Nigel will tell you, there was an established fracture line underneath the hosepipe. The broken gate is in the garage.
I suppose this is a sign from providence that it is time the fittings were replaced with your patented design as installed on Millie.
Thought you were still away so hadn't bothered to chase you up yet. What Chris says is correct -happened late on in the club rowing. It's a stress fracture enhanced by low oxygen levels (post was wrapped in braided pvc hose). At failure only ca 25% of post was unfractured. From corrosion state of (stress pre-)fractured part it appears fracture had been propagating for many weeks (if not months). Suggest all other posts are investigated for signs of fracture initiation.