Sliding down a gigantic tongue in an eye-wateringly skimpy pink leotard, Miley Cyrus kicked off her 23-date European tour with a burst of expletives.

She certainly started as she meant to go on. Within the first ten minutes, we had crotch-grabbing, grinding and yet more foul language — building to impassioned rants in which she encouraged drug-taking and kissed someone of the same sex.

Having foolishly agreed to take my daughter Elsa, soon to be 15, to the show at London’s O2 arena, I was to endure two hours of the most inappropriate display by a pop star I have ever seen. Only 20 minutes into the show, I was wincing so much I wished we hadn’t come at all.

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Crotch-grabbing, grinding and yet more foul language: Miley Cyrus performs at 02 Arena in London

The most troubling sight, though, was the number of young children in the audience — girls as young as nine, accompanied by bewildered and embarrassed-looking parents. And while girls of my daughter’s age and older did seem to relish the show — a worry in itself — some younger ones seemed genuinely disturbed by the raunchy antics.

One nine-year-old I spoke to admitted to being ‘in shock’ and not ‘understanding what she [Miley] is doing any more’.

You may well wonder why parents would take children to see the controversial Bangerz tour, particularly as it’s made headlines for all the wrong reasons since it started in Canada in on Valentine’s Day.

Although tickets specify under-15s must be accompanied by an adult, that hasn’t stopped the chaperones inundating the lewd singer’s management with complaints about the explicit content. Knowing all this, why did I allow my daughter to attend? Like many others, it comes down to a mixture of naivety and ignorance.

Elsa grew up with Disney’s Hannah Montana — of which Miley was the wholesome star — and has watched her transition from clean-cut girlie girl to international wild child. She was keen to see Miley’s only concert in London and, despite the star’s notoriety, I really hadn’t imagined it would be as extreme as it was.

Stupidly, I thought there’d be due consideration given to the young age of her fans.

Twerking girl: Miley Cyrus mixes childish images with outrageous routines

Shocking: Miley Cyrus wore a series of raunchy outfits during the first London night of her Bangerz tour on Tuesday – including this Union Jack embellished leotard

However, while there were nods to the innocent tweens in the crowd — and the parents who paid for their tickets — such as dancers dressed in fluffy animal suits and a giant kitten projected behind the stage, these were cynically juxtaposed with lewd dance moves and revealing outfits clearly aimed at a different audience.

I certainly wouldn’t have taken Elsa had she been any younger. Her younger sister, Rosa, 11, pleaded with me to get her a ticket but I said no. And thank God I did.

As we entered the arena, we were hit by huge black and white ‘parental advisory’ signs hanging in the foyer. Not referring to the evening’s show, but to the merchandise: skimpy hot pants emblazoned with lasciviously dangling tongues and a near-pornographic poster of crop-haired Miley in a red thong leotard, with more warning notices covering her barely-covered crotch.

The £15 souvenir programme featured pictures of the 21-year-old sucking on a banana and revealing her bottom and breasts in a series of outrageous outfits.

Among the hordes of older teenagers wearing tiny hotpants and bare midriffs in homage, younger fans were also arriving with their mothers. Their fresh-faced innocence was in stark contrast to the seedy images all around.

I asked a few parents about their motivation for bringing their children. Lisa Minot, 46, from Essex was with daughter Bryony and her friend Eve Dobson, both 13. She said it was because the girls were fans of Hannah Montana.

She hasn’t changed: Miley performs provocative moves onstage at London’s O2 arena

They were warned: Miley has the phrase ‘Parental Advisory Explicit Content’ projected onto the stage

‘We’ve seen clips of the show in the internet so I feel quite prepared,’ she said. ‘I must admit I thought the video for the song Wrecking Ball [which featured the singer naked swinging on a wrecking ball and suggestively licking a sledgehammer] was a bit OTT but I was not too worried about bringing them here tonight.’

Charlotte Lane, 31, and Lisa Cox, 46, were buying programmes for their 12-year-olds, Lillie and Isabel. The tickets were a present from Charlotte for Lillie’s birthday. Both mothers came across as blasé.

Charlotte, a fitness instructor, brushed off my fears, saying: ‘Anything Miley does tonight, I am sure the girls will have seen worse on the internet. In any case, they are quite small so I am sure any really rude bits will go over their heads.’

Ironically, the children themselves seemed more clued up about why the show was a cause for concern.

‘I’ve loved her since Hannah Montana.’ said Lillie. ‘I like her new look, but the way she has been acting recently, she really embarrasses herself and goes too far.’

Tommy Burton, 33, an estate agent from North London who’d brought his nine-year-old daughter Evelyn, was more wary: ‘I only looked at online footage today and I have to admit I was shocked.

‘Evelyn was a huge Hannah Montana fan and would have been heartbroken if we had cancelled — but this show is in a different league. I think I will have to cover her eyes for some of it.’

She likes the high life: Miley wore Marijuana leaf shades with a gold chain to match

Bum deal: Miley couldn’t seem to resist flashing her derriere to her audience

Injured: Miley said on stage hat she had sprained her foot during her stint in hospital

There is no doubt Miley is selling tickets off the back of her more  palatable past and is to some extent reliant on parents’ head-in- the-sand approach to the content of her shows. At the same time, she is using explicit sexual imagery to pull in a different clientele.

It was this deeply cynical conflating of extremes — childish playfulness and suggestive cavorting — that dominated the concert, and made me most uneasy.

Dancing bears and huge Muppet-style puppets shared the stage with provocatively-clad dancers, including a female giant and a dwarf.

A bondage-inspired short film, ‘Tongue-tied’, featuring Miley naked apart from black tape on her nipples, was played while the image of a fluffy ginger kitten formed the backdrop to another number.

During the anthem Get It Right, Miley simulated an orgy with her male and female dancers on a candy-coloured couch while images of Smarties and jelly beans were projected in the background.

Before the song Adore You, she asked the audience if they ‘liked to get wet?’ before taking gulps from a bottle of water and spitting it over them. A heartfelt speech about the recent loss of her dog, Floyd, followed.

Confused? I certainly was. But when I looked around, the teenage fans surrounding me were having no such problems. Unsettlingly, Elsa looked swept away as well.

Still with the tongue: Miley took a selfie onstage during the gig

Working out: No doubt the singer’s regime helps to keep her fit and in shape

She’s not shy: The singer once again flashed her bottom to the crowds

She was standing up, dancing and singing along to the songs. The only time she leaned over to me it was to shout: ‘She’s so much better than I thought she’d be.’ Oh God.

The costumes became ever more revealing. Sparkly thong leotards barely covered her modesty and she made repeated lewd gestures including crotch grabbing and, of course, twerking — the provocative, bottom-thrusting dance move which Miley has made infamous.

During the song Love, Money, Party, she humped a car and spanked her bare bottom, tilted provocatively towards the crowd.

It was at this point I realised my mistake in bringing Elsa — and I wasn’t alone. If the singer’s volley of crude remarks had my head in my hands, a couple next door to me got up and left — and  they didn’t even have children  with them.

Miley’s protruding tongue has become her trademark and I can see why. I tried to keep count of the number of times she used the F-word but lost count after half an hour.

During Adore You, she invited people to ‘make out with each other and use a lot of tongue’. Images of kissing couples — many of them same-sex — were then broadcast on giant video screens.

Worse still, for a singer with so many young and impressionable fans, was her undisguised praise for smoking: ‘I smoked for three years and I loved it’ and exhortation to the fans to smoke marijuana: ‘Weed is much better than smoking . . . this show’s nearly over and I will be stoned very shortly.’

The show ended with Miley suspended on a giant hot dog which transported her off the stage.

With the music still ringing in my ears, I caught up with Charlotte Lane and Lisa Cox, who’d been so relaxed about it all before. They had done an about-turn.

‘All that crotch-grabbing, particularly in the first half of the show,’ said Lisa. ‘I had never imagined it would be as bad as that.’

Charlotte said: ‘I thought it would be a bit rude but not at that level and not with young children in the audience. What I found particularly disappointing was that she was promoting smoking weed.’

What about my own daughter? Elsa concluded: ‘It was a really good show. I liked the bits best when she did more singing and was trying less to be a rebel.’

I didn’t know whether to feel relieved (perhaps a lot of it had gone over her head?) or concerned that she’s part of a generation that barely bats an eyelid at Miley’s cheap, sordid antics.