FOR many years now, I have slightly fan-girled one particular A-list star.

And as a showbiz correspondent of two decades, trust me when I say I am slightly jaded and, well, quite cynical to most celebrities’ charm.

This person, however, has true star quality. A once in a generation talent.

Gracious, magnanimous in interviews, obscenely multi-skilled and genuinely inspirational, they are rapidly achieving “national treasure” status. (Another term I do not use lightly).

Unfortunately, they are also a prize A horror.

Over the past couple of months, I have been contacted by five different witnesses, all begging me to expose this artist’s “true self”.

These are individuals who have worked with them on set and on photoshoots, and have witnessed, first-hand, episodes of and temper tantrums going back years.

Once the cameras stop rolling, off comes the shiny, happy veneer – quicker than the studio .

On one occasion they made an MUA (make-up artist) cry, and on another a different set – they arrived 90 minutes late and blamed their tardiness on junior members of staff.

When an AD (Assistant Director) raised their frustrations, and called them up on their time-keeping, they received the wrath of X. Within 24 hours, the AD had mysteriously “quit”.

Such is the power of this .

Other incidents allegedly include throwing an object at a crew member, bullying – something doubtless dismissed as “banter” – and regularly “belittling” cast.

When I started to investigate this person – whom I am not naming – I also spoke to one person who had had supremely positive experiences.

They described them as “charismatic” and an “inspiration”, adding: “when this person trusts you, they open up and can be enormous fun and hugely gregarious. I don’t have a bad word to say.”

And, of course, everyone has bad days. But this star appears to have many, many bad days.

As they say: “Once is a mistake, twice is a pattern and three times is a habit.”

In evidence, there are a lot of poor habits.

There are also numerous “micro-aggressions”, I am told: passive aggressive eye-rolling and general dismissive behaviour to anyone deemed unimportant.

Says one industry mole: “I am finding it increasingly frustrating seeing this person being lauded left, right and centre – people don’t know what they are really like.

“They have upset numerous people I work with, and friends of mine. They have made people cry, bullied others and just been deeply unpleasant at times.

“Designers often won’t work with them as they’re so demanding, and it’s telling that cast and crew rarely share their experience of working alongside them whereas usually celebs are plastered all over after a shoot.

“It’s just a real shame, and bad behaviour should be called out.”

Another added: “They are extremely fake. One thing when the camera rolls, and quite another when it stops. It is sad to see.”

To be clear, though, there is no suggestion of criminality. They just aren’t, perhaps, the nicest person on the planet.

Certainly I would not want to go head to head with this individual’s vociferous fanbase – nor their rottweiler agent. (They have a global team around them, with one especially grim US-based representative).

So, person X, if you’re reading this and recognise your behaviour. Please stop.

Let your talent do the talking – not those you regularly upset.