A hard-left protester who screamed ‘Nazi scum’ at a Donald Trump supporter who was covered in milkshake at a demonstration yesterday is a company boss selling private services to the NHS, MailOnline can reveal.

Siobhan Prigent owns a profit-making company which takes taxpayers’ money to provide clinical trial coordination at University College London Hospital (UCLH).

The 35-year-old yesterday apologised for her behaviour when she shouted at the grandfather as he was coated in the milky drink during protests at Parliament Square.

She now faces a battle to save her job at the hospital.

Siobhan Prigent, pictured, has apologised for her behaviour at a London protest today in which marchers yelled 'Nazi scum' at a Donald Trump supporter

Ms Prigent, who works as a clinical trials coordinator at University College Hospital, is seen holding a placard saying: 'This episode of Black Mirror isn't funny any more! #NoThanksNazis'

Ms Prigent – who sells project support services to the NHS through her company VLEK Ltd – was spotted laughing as the British Trump supporter, who has not been named, was attacked by the angry mob.

In the footage she is questioned about her shocking behaviour, to which she responds: ‘I don’t need to hear from other white men, thank you very much.’

The revelation that Miss Prigent is an NHS contractor comes amid Mr Trump’s suggestion that the NHS would be on the table in any post-Brexit trade talks.

Miss Prigent, who lives in London, describes herself online as an ‘intersectional feminist’ and a ‘crazy cat lady’ with an interest in mental health. She appeared to have gone to ground last night as she could not be reached for comment and had deleted all her social media accounts amid fears her NHS career was in jeopardy.

The 35-year-old yesterday apologised for her behaviour when she shouted at the grandfather as he was coated in the milky drink during protests at Parliament Square

A UCLH source said today bosses were weighing up whether to end her contract, though no decision has yet been taken.

The businesswoman’s social media profiles, which have now been deleted, contained a string of hashtags including #LGBTQIA and #IntersectionalFeminist.

A spokeswoman for the hospital said: ‘Siobhan Prigent is not a UCLH employee. She works for a third party contracted to carry out administrative work at UCLH. Her work does not involve patient contact.’

In video footage of the attack, Ms Prigent and a number of marchers are seen yelling at the victim before he is hit with the drink.

He tells the angry mob that he is 'here to stay' before throwing the empty cup back at them as a female police officer tries to stop it turning into a brawl.

Miss Prigent, from London, (pictured in the fracas) apologised in a now-deleted tweet: 'I am very sorry for my behaviour today. I should have protested peacefully & I didn't, & I regret that

Ms Prigent is seen holding a placard saying: 'This episode of Black Mirror isn't funny any more! #NoThanksNazis'.

Afterwards she apologised in a now-deleted tweet: 'I am very sorry for my behaviour today. I should have protested peacefully & I didn't, & I regret that.

‘I’ve let myself down & I do understand that fully. There are two sides to every story, but my actions were my own, & that’s on me. Please leave my family & friends out of it.’

Her apology comes after the Donald Trump supporter spoke out to reveal he was at the protest campaigning to protect democracy.

Speaking to MailOnline, the man, who refused to be identified, said he was peacefully debating with 'moderate lefties' and 'having a laugh with the majority of them' before the demonstration turned violent.

He said: 'We have to put forward how aggressive the left can be - it's not us, you know if they want to call me right wing because I'm supporting Trump then I must be right wing, but I'm not a racist.'

Speaking of the moment he was attacked, the man added: 'I came out to support Trump, to stop the left who since we voted for Brexit have been protesting against democracy.

'This is the democratically elected president of the free world. I just wanted a debate with the sensible left, I didn't expect any of what happened. I never wanted it to get violent, but I wasn't going to be intimidated.'

The grandfather said that the 'hardcore lot' became bitter 'because they couldn't answer the questions and the answers I was putting towards them'.

The pro-Trump supporter caught the milkshake before throwing it back during the protest against the President today. He told MailOnline he was there supporting democracy

He explained that one of his friends had been hit by a milkshake first, and he was hit while helping him.

The man also claimed he was kicked in the legs, and attacked with a banner with a stick on the end. The demonstrators also attempted to remove his Make America Great Again hat - which he eventually got back.

The Londoner told how police officers removed him from the protest on Parliament Square for his own safety.

He told police that he didn't want to officially report what had happened as he knew 'nothing would come of it'.

'Some of them started calling us fascists, and we was telling 'em you're the fascists protesting against a democratically elected president of the free world,' he told MailOnline.

He continued: 'They have their democratic right to be there, and protest against him, and it was peacefully protesting.

The pro-Trump supporter was escorted away by police for his own safety after demonstrators threw the beverage at him

'They was good to debate with and I was having a laugh with the majority of them then we started to get the hardcore lot coming in and start surrounding us.'

Earlier that day, the Trump supporter said the U.S. president made his 'grab them by the pussy comments' because he's 'still a kid at heart'.

Speaking to Joe.co.uk, he added: I see a link between Brexit and Donald Trump in globalism. Stopping globalism. I don't like the fact that there's globalism. I'm dead against that.

'I'm dead against unelected bureaucrats up in Brussels, who you cannot vote out. And they're forcing laws upon us that we don't even know about. I've no problem with Europe, it's the EU.'

The middle-aged Trump supporter claimed demonstrators kicked him in the legs, attacked him with a banner and attempted to remove his Make America Great Again hat. Moments after the middle-aged man was doused in milkshake, Miss Prigent was filmed yelling ‘he’s a f****** Nazi’.

The foul-mouthed protester has worked for the NHS for ten years and set up her own management consultancy business last September. She is the only director of VLEK Ltd which is awarded NHS contracts.