The UK, for reasons never explained to the pilot body, followed suit within months.
Are you sure? I only remember the French being out of step with Europe's 65 with a 60 limit, extending even to foreign airlines overflying. That was never going to be enforced unless you landed on French soil. I also had an idea it was a pilot union initiative, not the XAA. I think EASA rules have changed that. There were company pension funds and employment contracts that restricted the retirement age to <65, but I don't think any XAA outside France did so. To be corrected.
It's an interesting conspiracy theory about the FAA. I thought Aalpa had considerable power & influence over such issues. After all, it would have had great financial impact on crews nearing pension age & costs.