As launch parties go in these more straitened showbiz times, it was extravagant and very, very glossy.

Held at an expensive rooftop bar in London’s recently renovated King’s Cross, the 100 or so guests invited to celebrate Graham Norton’s ITV show The Neighbourhood were treated to non-stop cocktails, fizz and canapes.

With the man himself as the event’s ebullient host, it was clear ITV bosses, giddy from signing the BBC’s golden boy for their big new reality show, anticipated they had a ratings winner on their hands.

Norton, of course, fronts a highly successful BBC1 chat show and ITV were confident he would provide the star power to make The Neighbourhood –which follows families competing for a £250,000 cash prize – a phenomenon to rival BBC’s The Traitors, hosted by Claudia Winkleman.

But in an embarrassing U-turn, less than two weeks after its first episode, ITV relegated The Neighbourhood from its 9pm primetime slot on Thursdays and Fridays to the 10.45pm ‘graveyard’ slot, amid poor reviews and plummeting ratings.

A TV insider told me: ‘It’s all pretty embarrassing for Graham, it was all announced with such huge fanfare, ITV bosses were parading him round like he was the King or something.

‘Graham is so good at hosting a chat show, it’s his natural home, but this has shown that maybe other projects, such as reality television, aren’t where the viewers want to see him.

‘He tried to keep up with Claudia by taking on a show which ITV hoped would be their version of The Traitors but it has failed.

‘In fact it’s the opposite for Claudia Winkleman, she’s perfect for Traitors but her chat show made little impact.’

For, in a nice bit of A-list symmetry that also illustrates the entwined world of Britain’s TV stars, Claudia (who is Norton’s friend) launched her own chat show earlier this year.

Made by his production company, it even occupied his Friday night slot while he was filming The Neighbourhood, meaning both stars now have a chat show and a reality show each.

Whether entering each other’s sphere has boosted – or damaged – their careers is another matter, however. Claudia’s chat show was widely panned, too.

The Neighbourhood was filmed on a specially built set in the Darwin Lake Holiday Village in the Peak District, where ten families lived cheek by jowl and, like The Traitors, competed in various challenges – hunting garden gnomes, being strapped to their washing lines – all while trying to keep their rivals onside to avoid, in the parlance of the show, ‘removal’.

The launch attracted 1.2million viewers. However, by the third episode, just 500,000 were tuning in.

Viewers were scathing on social media, branding it ‘drivel TV’, echoing the reviews of TV critics. One described it as a ‘tedious’ imitation of The Traitors.

Such criticism is something Norton isn’t at all used to. His eponymous BBC chat show will mark its 20th anniversary next year. Since its 2007 launch it has won four Baftas and is the ‘go to’ show for Hollywood royalty – from Ryan Gosling and Tom Hanks to Lady Gaga and Taylor Swift. He is widely regarded as the best chat show host in Britain.

As such, television insiders say that this flop is ‘a disaster’ for the 63-year-old television veteran whose career has spanned 44 years. Until now, everything he touched had turned to gold.

‘This is a huge blow for Graham,’ says my source. ‘For so many years he has been one of the most popular stars on British television. But you have to start to wonder now whether his crown has slipped. It is quite inconceivable that someone so adored, who is watched by millions on the BBC, couldn’t make The Neighbourhood work.’

One source familiar with Norton was surprised to learn that he was to host a new show at all – because he doesn’t need the money. He is reported to be worth an eyewatering £30million thanks to The Graham Norton show, for which he is said to earn around £116,000 per episode. ‘It was a risk,’ says a TV insider. ‘Why bother when you’re that rich?’

Indeed, the star claims his decision to host The Neighbourhood was not about money. Speaking before its launch, Norton said he initially agreed to meet producers with a view to eventually declining the hosting job.

However, in a rare misstep, he admitted he thought it was ‘so good I have to say “yes”’.

Norton, who also hosts the reboot of ITV’s Wheel Of Fortune – which has had nowhere near the success of its previous incarnation – has been seen as such a ‘pull’ by ITV that he was picked to host the showcase of their forthcoming programmes at London’s Design Museum a fortnight ago.

The lucrative role saw him interview the likes of Michelle Keegan and Gemma Arterton about their new shows in a room packed full of journalists.

While, as usual, he had his audience laughing away, some were alarmed by his puffy, red face.

One of my fellow showbusiness journalists whispered: ‘He looks tired, doesn’t he?’

Indeed, away from the cameras I hear that Norton and his husband of four years – Scottish filmmaker Jonathan McLeod – have left their home in Wapping, east London. Former neighbours say they were surprised to see them go but that they are ‘in search’ of something different.

This has prompted concerns that maybe Norton is looking for a different lifestyle.

But back to ITV and I hear that for its upper echelons the failure of The Neighbourhood with viewers has been a ‘huge disappointment’. Given Norton was at the helm they would have been very confident about its future. 

My insider says: ‘So much money was ploughed into the programme. It was a priority show for them and they had very, very high hopes. To say it has been a shock to some of those at the very top of ITV is a massive understatement.’

Internally, its apparent failure has caused ructions at ITV. Last year, there was a staffing bloodbath at the channel’s daytime department with more than half of the staff working on This Morning, Lorraine and Loose Women made redundant.

While it is not known how much Norton was paid for The Neighbourhood, there’s anger that money appears to have been wasted on the programme while around 300 staff lost their jobs.

‘It is galling,’ says my source. ‘Graham will have been paid a fortune for a show which has bombed, while some of ITV’s most talked about programmes have been slashed.’

Meanwhile, Norton recently revealed his chat show had been green lit by the BBC for a further three more series, which will begin with season 34 in the autumn.

His loyal fans will be hoping to see him back to his old self on his own show, a glass of wine in hand, rather than hosting a Traitors tribute act.