An extraordinary thing happened to me on a recent flight to Madrid: I unwittingly travelled under the wrong identity, becoming a potential security issue, and no one realised.

I was packing for a short business trip to make a film for the BBC when I attempted to check-in online. It didn't work, so I headed to London Heathrow Airport to do it in-person.

Upon arrival there, I tried once again to check myself in, this time at a self-service booth. Again I was denied, the machine flashing up an error code: "Assistance required."

I ended up at a check-in desk and after checking in my bag, a British Airways staff member handed me a boarding pass. Admittedly I didn't read the pass in any detail, but headed off to get processed in the security area as normal.

At the gate, I was among the first passengers to board flight BA7055 departing at 10:50 on 23 April, operated by BA's Spanish partner carrier Iberia, as I was in row six.

Dutifully, I handed my passport and boarding pass to a member of BA ground crew, who glanced at them both and waved me through.

Once on board I realised my seat was in business class. I assumed this must have been a free upgrade, because I would of course usually have been in economy; we had chosen this flight because it was the most cost-effective option with all our filming equipment.

No sooner were we off the tarmac and at cruising altitude than the delicious baked cod and chickpea stew lunch was served. Tiramisu for dessert, too. No complimentary alcohol for me though; it was a work trip.

It was on arrival in the Spanish capital when things started to go wrong.

As soon as I gained mobile signal on the ground, an email popped up: my return flight had been cancelled.

I asked the BBC's travel provider what had happened and what the plan was for getting me home?

In response, the travel company said it had been cancelled because I was a no-show on the outbound flight.

I explained that I was in fact very much in Madrid and waiting - endlessly, it seemed - to collect my checked luggage from the baggage belt.

After some no doubt confusing conversations between our travel team and BA, I received a further message to say the airline was adamant I had not travelled and that the boarding pass in my possession did not display the correct details.

This was when I realised that the name on my boarding pass was not mine, it was a man called Huw H. The BBC is not using Huw H's full name, which was printed on the pass.

His name was also printed on my luggage tags.

BA claimed there was no way I could have travelled using that document as security checks wouldn't allow it - but I did. My colleague, who was seated a few rows behind me, can vouch for me being on that plane.

The airline was so sure that I was not in Madrid that the BBC had to book me another seat on the flight home I was originally booked onto, at great expense. BA has since offered a £500 goodwill voucher as well as refunding the cost of the extra ticket.

The security protocol for passengers boarding flights is relatively simple: ground crew must check the name on the boarding pass matches that on the passport presented.

This process appears to have broken down in my case - with no one at check-in or the boarding gate identifying the discrepancy between the name on the boarding pass and my passport.

So what went wrong, and who is Huw H? I tried to find out.

Some internet sleuthing brought limited proof of Huw H's existence. I made a few attempts to contact accounts using his full name via various social media channels, to no avail. It's made me fear that he might not even exist.

I did manage to get in touch with someone with a similar name - Jonathan Huw H - who, it turns out, flew on a BA flight on 24 April, a day after mine, landing at Heathrow, so is it possible his name was somehow floating around in the BA system? "It's really worrying," Jonathan told me.

My married name, which was on my booking confirmation and passport, begins with the letter H - though is very different to Huw H's surname. Could this have factored in?

It's impossible to know, and BA cannot confirm anything for privacy reasons.

Simon Calder, travel correspondent at the Independent, said it was to be expected that mistakes will sometimes happen "in the high-pressure, deadline-strewn world of aviation".

But he added: "This case is unusual in that the error wasn't picked up at the departure gate, where it could have been easily rectified.

"The airline needs urgently to investigate and make amends."

Aviation security and operations expert Julian Bray added: "There is a security issue here, in that the plane took off with an incorrect passenger manifest.

"It is wrong and shouldn't have happened. The passenger manifest should be correct as it is an important document that shows who is travelling and where. That said, as the name on the baggage tag matched the one on the boarding pass and the correct number of people were on board when the plane took off, I can see how it happened."

Others would argue that it was not a security risk, though, because both myself and my luggage went through all the usual security checks.

A spokesperson for BA, which managed my ticket as well as the Heathrow ground crew in my case, said: "We've contacted our customer to apologise for this genuine human error. While incidents like this are extremely rare, we've taken proactive steps to ensure it doesn't happen again."

Meanwhile, the Civil Aviation Authority has told me it has launched an investigation into what happened.

Heathrow Airport said in response to a request for comment that it was not responsible for the ground crew or anything else in my case, and security screening went ahead as normal.

Iberia, whose only involvement in my journey was operating the outbound plane and cabin crew, has not responded to a request for comment. As is nothing out of the ordinary, my passport and boarding pass were not manually checked on the plane.

Apologies and investigations aside, the question remains how this was ever possible in this day and age of high security.

On social media there are threads about this type of thing happening around the world in the past, but the mistake was rectified before take-off as there were two people trying to sit in the same seat.

What happened to me appears to be different as my name was seemingly replaced with someone who seemingly wasn't travelling to Spain that day.

I'm not sure I'll ever really know what happened, but one thing is for sure - I won't ever walk away from a check-in desk without reading every detail printed on my boarding pass in future.