Why do some people propose in public?

A wedding proposal is the most intimate of occasions - so why are a growing number of people proposing in public?

The traditional wedding proposal was a low-key sort of thing.

One might think of something in a restaurant or a peaceful garden. When it was in public, any bystanders might have been completely oblivious.

But now a slew of YouTube videos are testament to a wave of ever more elaborate and often very public proposals.

You can see compilations of proposals at baseball and basketball stadiums in the US. Some unkind souls have even gathered together the most notable refusals.

And the flashmob wedding proposal - a craze which may have begun in the US in 2009 - is increasingly popular in the UK.

In November 2011, a marriage proposal which featured a hired choir on a packed London train was viewed by millions after taking off on YouTube.

Public proposals come in other forms too. One man opted for the confined space of an aeroplane and took control of the tannoy system to propose to his girlfriend. The other passengers were also happy when the woman said yes - they got free champagne.

The Blossom Street Choir has taken part in a number of very public proposals. Director Hilary Campbell says it costs between £400 and £2000 to hire a choir and that there has been a marked increase in the number of people proposing this way.

The choir played a part in Jimmy Hill's proposal to his girlfriend at Piccadilly Circus, in the heart of London in front of a crowd to the strains of (Your Love Keeps Lifting Me) Higher and Higher. The 60 people also included friends and amateur singers who had responded to a Facebook call for volunteers.

Hill, 22, got down on bended knee under the watchful gaze of the statue of Anteros - the Greek god of requited love, commonly mistaken for Eros. Josie Stanford, his girlfriend of six years, said "yes" without hesitation.

"I knew it was going to be big because I know what he's like. But I didn't know it was going to be that big," Stanford says.

While that particular recipient was delighted, albeit self-conscious, such a proposal is not for everyone.

"You would either be thrilled or mortified by something like that, depending on just how gregarious you are as a person," says celebrity wedding planner Siobhan Craven-Robins.

"But ultimately it's very romantic - well, it shows great organisation anyway."

Are sporting events a good place to propose?

The public proposal is part of a growing trend away from tradition, suggests Craven-Robins. It spread to the UK when rules on where you could get married were relaxed, allowing couples to tie the knot in places such as castles, hotels and stately homes.

The increased level of expectation that surrounds weddings these days has led to people feeling that their proposal also has to be out of the ordinary, she says.

Glenn Wilson, a consultant psychologist, thinks public wedding proposals may sometimes be a ploy on the part of men.

"It's possible that some men think that this will pile pressure upon her and increase the likelihood of getting a positive response, that she must think that he really loves her if he goes to this extent of trouble and trickery."

The recipient of the proposal, put on the spot before an expectant crowd, may feel rather constrained in how they can respond.

"There is tremendous social and public pressure behind the woman to say 'yes'," says Wilson. "If she says 'no' so publicly it's difficult to revise that response later.

"There's a danger that the guy will get the right response for the wrong reason. It does put her on the spot."

The craze for elaborate proposals does not just mean public. Even choosing the top of mountains or towers, or far-flung beaches, still represents a break from tradition.

Debrett's etiquette adviser, Jo Bryant, says public gestures should be fitting to the situation and the recipient should be comfortable with public attention.

"A public proposal that could be particularly loud, intrusive or embarrassing for people to watch should be avoided."

And not everyone is impressed with the long history in the US of men proposing during the interval of sporting events.

Rick Morrissey, a sports writer with the Chicago Sun-Times, had described such proposals as "one of the scourges of modern society".

He continued: "Any time these clips are shown on TV, a news reader coos, 'Awwwwwwwwwwww'. I reach for the cyanide capsules."

Despite the pressure of the situation not all public proposal recipients go along with the plan. At this NBA basketball match the woman said "no" and was booed by the crowd, while the distraught man was consoled by a giant cuddly mascot.

The result is YouTube fodder, as much as the successful proposals make popular videos. Wilson says people feel compelled to watch these videos for the same reason they watch reality TV.

"They are just entertaining, to see real things happening to people."

Georgia Tolley, editor of the Before the Big Day wedding blog, got engaged six months ago and describes her fiance's proposal as being "a very lovely, very private moment".

While "very beautiful", a proposal like Hill's would not have been for her. "I would have died of embarrassment. I'm very English, I would have been mortified."

Tolley says she does not see the trend taking off in the same way it has in the US.

"In America people are a lot more showy-offy and outgoing and that's a fantastic side of the American culture. Here in the UK I just can't see people really engaging with it. I've seen some of the films and the girls just look like they want to fall into the ground.

"You're going to have your wedding, there's going to be loads of opportunities for you to rub your love in other people's faces and go 'look, we're fantastic, we're perfect, we're an amazing couple'. You don't need the bells and whistles. It's a pretty cool moment as it is."

Jimmy Hill and Josie Stanford appeared on the BBC World Service programme Newshour.