Image copyright Getty Images

Party leaders and their campaign organisers have got many things to worry about on the election trail - but how important are their clothes and what can we be looking out for during the general election campaign?

No politician wants to look as though they are overly interested in how they dress.

"You'll see I wear only grey or blue suits," President Barack Obama once said.

"I'm trying to pare down decisions. I don't want to make decisions about what I'm eating or wearing. Because I have too many other decisions to make."

And few voters would want to admit that politicians' clothes have much of an influence over how we vote.

The problem is, experts tell us, that with the clothes we wear we are constantly giving off and receiving signals - whether we are conscious of it or not.

'Speed, modernity'

Theresa May, a self-proclaimed lover of fashion, has had a long while to hone her choices while in the public eye - and to understand what messages she is conveying.

Her clothes have been a subject of hot debate for at least 15 years, when she caused a furore by wearing a pair of leopard-print kitten heels to deliver a Conservative Party conference speech.

Image copyright Reuters Image caption Structured tailoring, sober suits...

On the campaign trail, notes Dr Vanessa Brown, senior lecturer in design, culture and context at Nottingham Trent University, Mrs May tends towards, to coin a phrase, a "strong and stable" wardrobe.

It does not follow fashion too frivolously and suggests a woman who is in control and making rational choices - yet with a flash of "trying to connect through fashion".

She sometimes wears diagonal lines, which can denote "speed, modernity, looking forward" and is a fan of quite structured tailoring, allowing for some movement when interacting with the public and pounding the streets.

It's a style that's easier to wear than body-skimming clothing, without looking "fussy" or "soft".

Image copyright AFP Image caption Mrs May's shoes have long been the subject of scrutiny

What about the famous shoes? Will we be seeing some flamboyance there?

Possibly, says Dr Brown, though noting that Mrs May's famous flashes of fun in her wardrobe are only "allowing that level of frivolity as far from her head as she could make it".

'Authenticity'

Jeremy Corbyn has also come under scrutiny for years over what he wears - although for slightly different reasons.

Media playback is unsupported on your device Media caption Jeremy Corbyn defends dress sense in 1984

Way back in 1984 he was being given a dressing down on BBC television for "scruffy dress" - which he responded to while wearing a jumper knitted by his mother and criticising Tory MPs for voting in "dinner jackets".

Despite having so far worn thoroughly respectable suits while campaigning, the "scruffy" tag continues to haunt him.

One voter told a Daily Politics vox pop in Derby this month that Mr Corbyn looked like he'd "come out the back garden", comparing him unfavourably with David Cameron, who was "smart".

"I'm not saying I wouldn't vote Labour, but that has a big influence," said the voter.

On the other hand, Mr Corbyn's clothes seem to appeal to parts of the electorate. Pop culture site Konbini recently ran a piece on how to look like him, with tributes to his oversized blazers, Breton caps and "bicycle chic".

For politicians, you can't appeal to every single voter - so perhaps the important thing is to be "authentic". If you look like your natural self, Dr Brown says, people will find you more likeable, and in turn more believable.

Mr Corbyn, she said, could perhaps "sharpen it up" a bit to make his look "a little more intentional" - and Lib Dem leader Tim Farron, who is similarly normally seen in a suit, with or without a tie - could also "get away with a bit more".

Image copyright PA Image caption Tim Farron in hi-vis jacket AND a baseball cap

Mr Farron looks "exactly what he is", she notes, so presumably would score highly on any authenticity index - but could perhaps play up any subversive side if he wanted to be more noticeable.

He is reported to wear Dr Martens every day, with the Mirror at one point saying they "almost suggest this man has flair, personality... hobbies".

Image copyright Reuters Image caption David Cameron keeps it casual to feed a lamb

Mr Farron could perhaps, if that was the way he wanted to go, play up his reported musical roots.

He told the Huffington Post in 2015 that in the late 1980s he had fronted a band "written off as a fourth-rate New Order" , and told Total Politics that he was "once nearly a pop star" - explaining that his band got offered a recording session with Island Records, but didn't do it.

On the campaign trail he has so far not caused a particular stir, sartorially - although he did get his pictures in a lot of media outlets when he boarded a hovercraft in Burnham-on-Sea, clad in a lot of safety gear.

Politicians on the campaign trail do try to signal connectedness with voters by dressing according to their surroundings - for instance by dressing down if they are visiting a refuge or charity centre.

Or think David Cameron wearing casualwear while playing with a lamb during a campaign visit in his Witney constituency in 2015.

But go too far, it seems, and you will lose that sense of your authentic self - politicians still wince at William Hague's baseball cap, and that was from way back in 1997.

The scrutiny

But what about the formal events - the podiums and set-piece interviews?

Image caption Legs-It: We should move away from a focus on appearance, says Ms Sturgeon

What is often overlooked is how clothes make you feel, Dr Brown says.

Suits, with their structured tailoring, provide an impermeable smooth "outer casing" - a harder surface which can make you feel stronger and more in control.

That's why tailoring and monochrome colours are so popular - they not only don't look like you're fussing - they literally make you feel more invulnerable.

Although men are also increasingly under scrutiny for how they look, it is still women's clothes that are really picked on and pored over.

An enormous amount has been written about SNP leader Nicola Sturgeon's clothes in the last couple of years - the Daily Mail's recent "Legs-it!" front page, comparing the legs of the prime minister and Scottish first minister while they were meeting to discuss Brexit and a second Scottish referendum, being a case in point.

Ms Sturgeon - who, like Theresa May, has appeared in Vogue and does say she is interested in fashion - has said she is conflicted by the scrutiny she comes under and that there is too much focus on what women wear.

"I do have a concern that for women, if women politicians - prime ministers, first ministers, are always reduced to how they look, and what they wear, and their legs, then we're saying something that we probably shouldn't be saying about the status of women," she recently told BBC Breakfast.

"So I think that focus on appearance is probably something we should try to move away from."

Perhaps that scrutiny partly influences her and other women politicians' fondness for single-colour suits and tailored dresses.

Minimalism, says Dr Brown, tends to appeal to politicians. All the scrutiny can lead to quite similar wardrobes of plain styles - because the more you experiment, "the more potential mistakes, more for people to talk about".

"So a shift dress is where you end up".

'He's wearing clothes'

It's almost enough to make you feel sorry for politicians - having to convey, through their outfits, all these messages about control, intelligence, entitlement to power, authenticity - while still trying to make people want to vote for them.

Image copyright Reuters

And you can't really say it doesn't matter because, as Dr Brown says, often for politicians a few words and their appearance are more significant than the depth of what they might say.

Most of us don't engage very deeply in the detail of political offerings - "so what else are people going on?"

But of course, not everybody goes in for the idea that clothes are a set of signifiers, sending off complex unconscious messages.

UKIP leader Paul Nuttall, for instance, has been notable for wearing a lot of tweed - a hint, perhaps, of Britishness and a traditional lifestyle - although so far on this campaign trail he has mainly been photographed in a dark blue suit and tie.

Is there a particular message he is trying to convey through his clothes, BBC News asked?

"No," said UKIP head of press Gawain Towler.

"He's wearing clothes, because some suit the outside and some suit the inside, just like you and I would wear clothes."