Mobile phones are without doubt one of the greatest inventions ever. The very fact that within seconds you can be talking to anyone on the planet is one of the most astonishing achievements of our age.

But mobile phones can also be hugely annoying.

Actors know only too well of the moment in a play when they have the audience right in the palm of their hand, hanging on every word, only to hear an irritating ringtone go off in the stalls and some buffoon say “I can’t talk now I’m watching a play…”

Or worse still completely ignore the offence and just let it ring out in the anonymity of their pocket or bag. Indeed some actors including the late Richard Griffiths during a performance of The History Boys at the National have stopped the play and berated the person in question.

And it’s not just theatres where mobile phones ruin the show, it also happens on sightseeing tours.

For years I was a tour guide on the Big Bus, London’s premier open-top bus company and I can tell you there is nothing worse than being halfway through your piece de resistance on the Tower of London or St Paul’s Cathedral than to hear the dreaded ringtone.

It once happened to me so often on one tour that I decided to take action with unexpected results.

It was a beautiful Indian Summer morning in late September and my bus was packed with a group of Norwegians from Oslo. They had got on at Piccadilly Circus and were led by a very tall blonde woman in her 50s wearing bright purple Dame Edna Everage style glasses. She rarely smiled and tended to bark at her group like some sort of Scandinavian sergeant major.

The group itself were polite and interested but as we got down to Big Ben and the Palace of Westminster, one of them took a call on his mobile phone.

Now there is nothing a tour guide dislikes as much as a tourist on their phone. Suddenly you are competing with another voice. And it doesn’t matter what language that voice is in, other people in the group get distracted. It becomes very difficult to focus on what you are saying when people all around you are having private conversations with friends back home.

On this occasion I wasn’t too bothered as the person in question was sitting at the back of the bus. But by the time we had reached the London Eye, the caller had been joined by two more people chatting away to friends in the fjords about their holiday in London.

By the time we were approaching Pudding Lane, another three were yapping away. It was getting ridiculous, I even wondered whether they were ringing each other up. Obviously something had to be done.

I spoke to blondie, the group leader, about my concerns and one of her eyebrows shot into orbit. She yelled at her flock to end all calls which they did with impressive speed. Goodbyes were said and mobiles were obediently put back into bags and pockets.

I got back to telling everyone about the Great Fire of London.

By the time we had crossed London Bridge, however, ringtones were creeping back in and huddled Norwegians could be seen chatting once again to their chums back home.  I decided a new approach might be necessary.

As we came up to Tower Bridge, I popped downstairs and spoke to my driver Natasha. I told her the problem and instructed her to stop the bus at the next stop, switch the engine off and come upstairs where she was to ask me whether anyone was using a mobile phone because it was causing havoc with her dashboard dials (please note that this was in the early days of mobile phone technology and odd things did occasionally happen). I would then ask my tourists to switch off their mobile phones.

“I’m to say that my dials have gone wonky?” she double-checked, slightly confused.

“That’s it, Natasha. It’ll help me no end.”

Natasha said she would do her best and started rehearsing her small but vital part.

Sure enough, when we got to the Tower of London, the bus stopped and the engine went dead. Natasha raced up the stairwell and with a particularly anxious and worried look asked, “Miles, is there anyone up here using a mobile phone? Because it’s affecting my dials in the driver’s cab. They’ve all gone wonky.”

I accepted the feed line with equal over-acting, “Oh dear Natasha, how awful for you.”  I then turned to the tourists and repeated her question. “Ladies and Gentlemen, can you please switch off your mobile phones. Our driver Natasha’s dials are being affected. You really must put away your phones.”

There were puzzled looks all around the bus but all those on mobile phones ended their calls and, once again, returned them to bags and pockets.

I gave Natasha a wink and she went back downstairs as confident as an Oscar winner and started the bus up again.

I resumed my commentary and got back into a juicy story about the ghost of Anne Boleyn haunting the Tower carrying her head under her arm.

Unfortunately the statuesque group leader was not interested. Anne Boleyn and her detached head were of secondary importance. She goggled at me through her purple Dame Ednas and questioned the recent event.

“Mr Guide, can you explain how my group using their mobile phones could possibly affect the dials on the driver’s dashboard downstairs and make them go what-you-say... wonky?”

I wasn’t in the mood for this discussion and anyway, I didn’t have a reasonable explanation. “I’ve no idea,” I replied, “but that’s what our driver said so it must be true.”

But blondie wasn’t going to accept this. And by this time she seemed to have half the passengers on her side. Norwegian heads were nodding in support at their leader’s brazen challenge.

“No, no you don’t understand,” she said firmly, “we cannot understand how the dials could be affected.”

“Well they just are. Accept it,” I said feebly.

“But in our professional opinion...”

“And what might that be?” I enquired as politely as I could.

“We are all mobile phone engineers from Oslo...”

Oh. Stop the bus, I want to get off!