A patch of trampled undergrowth behind Caroline Nokes’ New Forest home was the final clue needed by a security consultant to support his theory the Tory MP had been under surveillance.

For almost two years the MP for Romsey and Southampton North has been the target of online attacks from Matt and Nadine O’Connor – the husband and wife partnership who run Fathers 4 Justice (F4J) – as well as their followers.

Late one evening, Mr O’Connor tweeted that “she can run but she can’t hide” and that F4J were in Romsey looking for her. He also posted messages saying that Ms Nokes should “be charged with child abuse”, while his followers sent death threats, saying they would burn her house down.

In June, the security consultant hired by Ms Nokes said he believed there was evidence supporting her worst fears. This was no longer just Twitter trolling, she was being watched, he concluded.

On Friday Ms Nokes will appear in a civil case brought by the O’Connors in the High Court against a former lobbyist, Adrian Yalland, and the MP. She is accused by the O’Connors of aiding Mr Yalland in stalking and harassing them, but she and Mr Yalland say the claim is a vexatious publicity stunt and the truth is exactly the reverse.

Matt and Nadine O'Connor of Fathers for Justice (Justin Sutcliffe/The Independent)

F4J could once claim to be the voice of a generation of shunned dads, their noisy superhero campaigns putting fathers’ rights at the top of the political agenda. In the initial years, after they were founded by Mr O’Connor in 2002, they lobbied hard for changes to the family courts and better rights for absent fathers.

Their unorthodox protest methods, including scaling Buckingham palace dressed as Batman and flour-bombing Tony Blair during Prime Ministers Question Time, have always attracted criticism. But now they are accused of neglecting their campaigns in favour of increasingly personal attacks on Ms Nokes and Mr Yalland, as part of a four-year saga which has seen their supporters send death threats, both sides trade allegations of harassment and resulted in a tussle on the O’Connors’ drive.

Ms Nokes first met the O’Connors before coming into office back in 2010. She was interested in family law and, as their local Conservative candidate, assisted them in their lobbying efforts, even setting up ministerial meetings for them.

Civility broke down after F4J were not allowed to give oral evidence to a consultation on the Children and Families Bill. Ms Nokes sat on the committee which drew up the bill, and says she asked the O’Connors five times to send her the written amendments they wanted. At this point the Twitter attacks started.

'Fathers for Justice' campaigners stand atop Harriet Harman's home, the group would also protest in this way a second time in 2008 (William Wintercross/Getty Images)

Speaking to The Independent about the abuse, Ms Nokes says: “I’m perfectly relaxed about a bit of political argy bargy, but they weren’t interested in having a debate about the Children and Families Bill and what it was and wasn’t achieving. It very quickly degenerated into them just hurling abuse.”

When Ms Nokes’ friend Mr Yalland waded in to defend her on Twitter, he too became a target. Mr Yalland first met Ms Nokes at the Romsey and Southampton Conservative Association. He invited her as one of three MPs on a controversial trip to Equatorial Guinea in 2011 when he was working for a lobbyist representing a think-tank – Triarus – that was probably a front for the country’s dictatorship. The MPs came back with a critical report about the regime.

The O’Connors posted offensive messages about the nature of Mr Yalland and Ms Nokes’ relationship on Twitter. In April last year they openly declared “war” on Ms Nokes and Mr Yalland in a tweet.

Such was the barrage of vindictive tweets that in June the official F4J account was suspended by the website and Matt O’Connor’s was closed completely. F4J claimed the suspension was political censorship.

According to Ms Nokes, the worst messages often came not from the O’Connors but their followers. Three of the most violent threats made on Twitter were reported to the police by Ms Nokes, who later decided not to press charges.

Fathers 4 Justice threatened to disrupt Olympic events outside the capital in 2012 (PA)

The police told Ms Nokes they regarded the O’Connors as a “fixated threat” and a credible threat to her and her teenage daughter’s safety. Following advice from a security consultant, who, along with the local police, had assessed her home’s safety, Ms Nokes had several thousand pounds worth of security improvements installed in June.

Ms Nokes feared that the O’Connors were spying on her. A private detective has told The Independent that Ms O’Connor called him up at the start of this year to enquire about surveillance costs and vehicle tracking of “a Tory MP”. He said “[Ms O’Connor] was ranting immediately and asking if we had any affiliation with the Tory party. She started talking about surveillance costs and vehicle tracking.” He decided not to take her on as a client because he had reservations about tracking an MP and thought she “sounded difficult” .

Ms Nokes’ own private security consultant said: “There were patches of land behind the house that had been trampled and it looked like surveillance.”

He added: “I’m also pretty certain that somebody at some point has put a tracking device on her car.”

There were several coincidences that raised Ms Nokes’ suspicion of a tracker, she says. One of these was in June when, while visiting a school and deliberately not posting anything on the internet about her whereabouts, Matt O’Connor, protesting outside her office, was heard by her staff saying over a loudhailer: “We know she’s in Eastleigh.”

Conservative MP and the self-appointed champions of parental rights Caroline Nokes (Rex Features) (Rex)

Former F4J member Paul Triggs told The Independent that the surveillance was part of a bigger plan. “Matt O’Connor was planning to put activists on the roof of Caroline Noakes’ house and had her private address watched for several weeks,” he said.

Ms Nokes says she and her daughter still live in fear of what the group might do. “I am terrified now, following on from the death threats, of what they intend to do with me. They’re fixated, sad individuals who will stop at nothing.”

Mr Yalland was given similar treatment, with Nadine O’Connor using her blog to make accusations about his professional and private reputation. She and her husband wrote to Mr Yalland’s business colleagues and his employer, alleging criminal business practices and making assertions about his personal life.

After an allegation was posted online that Mr Yalland had been harassing the O’Connor’s eight-year-old son, he too was sent a death threat by one of their followers.

Mr Yalland says the O’Connors’ campaign of harassment has “destroyed my life”.

In December he suffered from a full cardiac arrest, which he says came as a result of the stress caused by their campaign against him.

Mr Yalland decided to start a libel suit against the O’Connors over the rumours they had been spreading about him. But, Mr Yalland says, despite trying multiple email addresses and posting the libel papers by recorded delivery, he could not get acknowledgment of receipt. So he decided to go to their house and deliver the libel suit by hand.

A memorable campaign from the group in 2003 (Getty Images)

On 20 February Ms Nokes gave Mr Yalland a lift from London to Stockbridge, where the O’Connors live. She dropped him on the outskirts of town and he walked to the O’Connors’ home on the high street.

What happened next is the subject of Friday’s lawsuit. The O’Connors accuse of Mr Yalland of causing injury, unlawful trespass, breach of privacy, stalking and harassment, and Ms Nokes of aiding and abetting him. They say that he photographed and traumatised their eight-year-old son. They say no legal papers were served on them and that as a trainee lawyer Mr Yalland would know that legal papers can be served by post, or indeed by the court.

Mr Yalland says the only pictures he was taking on his mobile phone were of the house to make a record that he had served the libel papers. He had returned to their driveway to take the photographic record after posting his legal letter moments earlier. At this point he says Mr O’Connor then barged into him, being aggressive and abusive, and took his phone. Mr Yalland says he was punched and pinned down by Mr O’Connor and his landlord, and that he then defended himself. The O’Connors claim Mr Yalland assaulted Mr O’Connor and that he bit their landlord.

In a blurry video posted online, which seems to have been filmed on Mr O’Connor’s phone, the F4J founder is helped up off the ground and goes to the house to tell his wife: “I’ve been assaulted, I’ve been smashed in the face”.

Fathers for Justice protest on the roof of Harriet Harman's home in 2008 (Getty Images)

Mr Yalland was held on suspicion of assault, after the O’Connors called the police, but was released on bail and the charges were dropped. Further attempts by the O’Connors to charge him for harassment and criminal damage were also thrown out, even after the Crown Prosecution Service reviewed the evidence three times at the O’Connors’ request, according to Mr Yalland.

Recalling the events, Mr Yalland said: “I naively thought I would just pop the papers through their letter box, take a picture and sling my hook. I didn’t for one minute think I’d end up arrested just for defending myself from two men.”

Mr Yalland has now successfully sued the O’Connors for libel after they failed to respond to the case he filed. In December the costs and any damages awardable to him will be decided in court.

At a public meeting, Nadine O’Connor has accused the Hampshire Police and Crime Commissioner, Simon Hayes, of orchestrating a cover up.

She said: “I can assure you that my child does not sleep at night... we are here today because we have no confidence in your police force and you have silenced us.”

The bemused commissioner replied that he was “not aware of your children being subject to criminality in your house”. He added: “You have in my opinion made things up.”

A supporter of the Fathers 4 Justice campaign marches in London near Christmas, timed to highlight the difficulties the time of year caused in 2005 (Jeremy O'Donnell/Getty Images)

He also described the pattern of harassment directed at him, saying: “You’ve pursued me on the internet and on Twitter, you’ve called for my resignation. You’ve actually, in my view, made up things.”

The O’Connors did not respond to repeated attempts by The Independent to obtain comment from them.

Former members of F4J say they feel the organisation has lost its way. The group has become increasingly marginalised and the only politicians to deal with them recently are George Galloway – who tabled an Early Day Motion on their behalf earlier this year – and Ukip, who met with Ms O’Connor in May.

Other family groups, such as the single-parent charity Gingerbread and the parenting forum Mumsnet have also been targeted by F4J. Earlier this year a F4J advert said Mumsnet “promotes gender hatred”, and labels “men and boys as rapists, paedophiles and wife beaters”.

The lobby group has never been made into a charity and the only shareholder of Fathers 4 Justice Ltd is Mr O’Connor. Former insiders say the number of paid members is now fewer than 200, but their website claims 40,000 supporters.

A splinter group, New Fathers4Justice, was formed in 2008 by those who fell out with the O’Connors. They say they are fed up with the group being sidetracked by personal attacks.

Former F4J member Paul Manning, who became disillusioned after what he saw as a lack of support for him in court, wrote recently: “Surely it is obvious to anyone with a pea for a brain that Matt O has lost the plot and purposely aims wide of the target that he originally planned on hitting. I believe that target had something to do with parental rights... The Matt O’Connor show is a huge joke to most of us now, because we see that what really matters to us and takes precedence to us is Dads seeing their kids.”

* Comment from Matt O’Connor (added 27 November 2015)

The claim that I was “planning to put activists on the roof of Caroline Nokes’ house and had her private address watched for several weeks” is untrue. At no time have either I or my wife Nadine or, as far as I am aware, anyone from Fathers4Justice been to the home of Ms Nokes MP uninvited, nor planned to put activists on her roof. Neither have I nor my wife planned to place a tracking device on her car as the article suggests. Fathers4Justice has no membership roll, no activists and no knowledge or record of a ‘Paul Trigg’.

With regard to Ms Nokes’ claims about me and my wife being a threat to her safety, I would like to make clear that neither I nor Nadine has ever been questioned, interviewed, arrested or charged by police regarding any matter relating to Ms Nokes or any member of her family.

As your piece makes clear, the one person who has been arrested in connection with this dispute is Mr Yalland, who was held over the incident at our home which your report describes. Ms Nokes drove Mr Yalland to our village on that occasion.

Legal proceedings remain ongoing in relation to that matter, and in addition a claim for libel has been issued against Ms Nokes.