Image copyright AP Image caption Pop stars like Justin Bieber are seen as potential role models - MPs less so

It's a familiar refrain when a pop singer or a sports star gets into trouble. They are supposed to be a role model, critics say, and they have abused their position and let everyone down.

But not everyone in the public eye generates this reaction when they misbehave. Politicians, even the famous ones, seem to be rarely considered in this way.

People might react with anger - or just roll their eyes - but the term "role model" is rarely used. Why not?

As well as selflessness, integrity, objectivity, accountability and openness, MPs are required by their code of conduct to show leadership - and to promote such qualities "by example".

This certainly sounds like role model material. But the message isn't getting across, says 20-year-old Chante Joseph, a former member of the National Youth Parliament.

Image copyright UK Parliament/ Roger Harris Image caption Chante Joseph was a member of the UK Youth Parliament for Brent in London

Part of the problem is that MPs are "from a completely different world" to most young people, she says.

"Young people are not really saying 'I want to be Theresa May when I grow up'."

Miss Joseph points to the lack of votes for 16-year-olds as an example of the disconnect.

"In order for you to have a role model, you need to see something in that person that reflects you, so you think 'I could be like you.'"

MPs are doing good work, she believes, but they "don't communicate in a way that young people understand".

And they are unlike more conventional celebrities, she thinks, because they try to present themselves as being "flawless".

Image copyright All Sport/Getty Image caption Young people find it easier to relate to Lionel Messi than to most MPs

Speaker John Bercow has warned of young people being turned off by MPs' behaviour in the House of Commons, particularly during Prime Minister's Questions, when he regularly castigates them for shouting at each other.

"There are people who think culturally the atmosphere is very male, very testosterone-fuelled and, in the worst cases, of yobbery and public school twittishness," he said in a 2014 letter to party leaders.

"I don't think we should be prissy about this, but I am not sure we're setting a good example to the next generation of voters."

Far from holding them up as role models, the public has taken a dim view of MPs for a while, says YouGov's Joe Twyman.

Trust in MPs has "slipped away" with events like Black Wednesday, the Iraq War and tuition fee increases, he says, leaving MPs ranked with estate agents and journalists in people's estimations. And that's not the good end of the scale.

"Very few people grow up thinking they want to be an MP," adds Mr Twyman, drawing a contrast with famous footballers.

Media playback is unsupported on your device Media caption John Bercow, the Commons Speaker, tells off former Education Secretary Michael Gove

It's a similar message from Heather Wildsmith, who is a youth worker in Leicester and has never heard young people express a burning ambition to be an MP.

The 24-year-old thinks politicians are simply not "relatable".

"Speaking to a lot of young people in the past, they have strong feelings towards certain topics but are not sure how to address them.

"People do not want to be MPs because they are not sure how to get into politics or they are not sure what MPs do.

"When an MP does something wrong they have to resign - when a pop star does something wrong they are almost celebrated - it's almost as if MPs are perceived as not being human."

If young people don't strive to emulate MPs, age could also be a factor - the average age of MPs has consistently been about 50 in recent decades - although the 2015 intake included Mhairi Black, at 20 the youngest elected politician in Britain since 1667.

Her SNP colleague, and Parliament's second youngest member, Stuart Donaldson, says young people are increasingly taking an interest in MPs' work.

"Despite this young people may have a negative view of politicians because they do not feel their views are being properly represented," he says.

"There is also still a significant number of young people who do not know or indeed care about what politicians do.

"Politicians should be doing much more to reach out and listen to the views of young people and recognise the valuable contribution they make to society."