14 month falls under a reasonable warranty period, so you could've claimed that. In the EU at least you'd have a very good case and they wouldn't cause trouble.

It could've been something trivial though, lint tends to pile up in the back of the lightning port, eventually causing the problem you described. Poking the back of the port with a needle or something often helps.

I'm pursuing the retailer/credit card company under the consumer rights and consumer credit act in the UK but they're requesting an engineer's report stating this is a manufacturing fault which is very difficult to get.

Tried cleaning it, there's no dirt or anything in there

So you're in the EU, and Apple isn't helping you, nor is the EU bothering to enforce it's own laws.

I must say, I'm still wondering why Apple gets a pass on the "usb charging for all phones" laws.

Couldn't you demonstrate right there that the Lightning port wouldn't charge the iPhone? Seems like a pretty simple way to refute the technician's claim.

Sorry badly worded on my part - he meant in perfect condition apart from the fault (ie: we hadn't drowned it or dropped the phone to cause any issue) but couldn't do anything

To clarify, he said that he couldn't repair the iPhone (with you paying for it)?

yes, even if I paid for it. Only solution is to replace the device.

I've found it's highly variable depending on the person you get. I've had some people that are really great and just help me replace it or figure out options. I've had other people force me to reinstall the OS even though the issue is clearly hardware and then come back in a week showing the same problem.