Two of the UK’s best known genealogists have become embroiled in a High Court legal battle centred on allegations of defamation and harassment.

Daniel Curran, the star of BBC One’s Heir Hunters, is accused of posting defamatory messages on Twitter about a company run by Peter Turvey, whose company acts as consultants on Who Do You Think You Are?

Mr Turvey, 66, and his son Philip, who run Anglia Research Services Ltd in Ipswich, accuse Finders Genealogists Ltd and its boss, Mr Curran, of mounting a campaign of defamation and harassment against them.

One member of staff at Finders is accused of conducting an anonymous Twitter campaign in which Mr Turvey, was referred to “under the disparaging name of ‘Purvey’”.

Finders and Mr Curran, they say, have used fair means or foul to lure away clients and their potentially fat commissions.

But Mr Curran and his company dispute the claims and “make counter-accusations of their own”, London’s High Court heard.

Judge Patrick Moloney QC said both companies were in the business of tracing heirs to estates which would otherwise be forfeit to the Crown.

According to the Turveys, the trouble started in July 2014 when Peter Turvey and Anglia Research were targeted in an anonymous Twitter campaign.

The tweeter used the “disparaging name of Purvey” and the Turveys say there is evidence indicating that the Twitter accounts were created by a Finders’ employee. The plot thickened when Anglia was involved in the eviction of squatters from an East London property which was part of an estate they were looking into. In November 2014, the Turveys became aware that a defamatory petition had been posted online by one of the squatters.

The petition appeared on the website, Change.org, and YouTube before the Turveys succeeded in having it taken down.

The Turveys did not suggest that Finders or Mr Curran had been involved in the petition’s initial publication, said the judge.

However, they claim that Mr Curran was later responsible for postings under a pseudonym on the Which? website which included a link to the petition.

Mr Curran also faces claims he was responsible for a defamatory posting on Change.org.

According to the Turveys and Anglia, conflict blew up again in August last year, when a Finders employee sent an email to a prospective Anglia client.

The email named Philip Turvey and included much of the contents of the defamatory petition.

After that, the Turveys became convinced that, despite their earlier warning shots, Finders and Mr Curran were continuing with their campaign.

They were, it was alleged, intent on bringing the contents of the petition to the attention of Anglia’s prospective clients.

Anglia and Philip Turvey have already launched legal action against Finders and Mr Curran and Peter Turvey was planning to join in a second claim.

The various claims and counter-claims emerged as the judge considered disclosure of documents at a preliminary hearing.