Kinloss-based Flight Lieutenant Owen Morris is taking legal action against Dr Brooke Magnanti – his former partner of seven years – whose call girl diaries became a worldwide sensation.
The 37-year-old, while in a relationship with the RAF officer, blogged secretly about her experiences as a £300-an-hour call girl before unmasking herself in 2009.
Mr Morris previously sued a newspaper successfully after it published inaccurate reports about his conduct towards her.
But Mr Morris, 38, is now suing Ms Magnanti, who moved to Fort William last year with her husband.
A case involving Mr Morris against Ms Magnanti appeared in the Calling List of the Court of Session in Edinburgh this week.
The nature of the case is not revealed but a call to the Edinburgh solicitors for Mr Morris was directed to top defamation lawyer Campbell Deane. Glasgow-based Mr Deane declined to comment.
It is understood lawyers for the RAF officer are aware of reports of Ms Magnanti living in the Fort William area but as yet have no address for her.
An official at the Court of Session confirmed Ms Magnanti was not listed as having any lawyers presently acting for her, and her address was described as "whereabouts unknown".
Despite this, Ms Magnanti is keeping up her public profile. At 11am yesterday she tweeted about visiting Birmingham with her husband, writing: "Balti last night, Bullring today. Yes, we have made the pilgrimage to the husband's homeland. £brummielove."
Half-an-hour later, responding to another user saying she was paid more than him, she responded: "Ah yes, the writers are minted myth. I'll clear about 22k this year."
And in her biography for her newspaper blog, last updated on Monday, she wrote she "can usually be found kayaking the sea lochs of north-west Scotland".
The Sunday Times published an apology after the 38-year-old RAF officer sought £100,000 from the newspaper in relation to two articles in 2010. The publication paid him damages and legal costs.
Ms Magnanti's literary agents, Conville & Walsh, did not respond to repeated requests for a comment from the author yesterday.
Mr Morris was referred to as "The Boy" in her blog, which was later turned into a tele-vision series in 2007 starring Billie Piper. He was deeply upset when Ms Magnanti unmasked herself because he claimed his identity was revealed in the process.
He complained at the time: "At least she has her literary career to fall back on, but what about me? Brooke has outed me to my friends and family without giving me any warning. She has made a great deal of money from Belle de Jour, but I haven't received a penny and my life has been completely affected. She never asked if she could write about our life together and I feel humiliated."
The officer said he had chosen "to believe she was a geisha rather than a high-class call girl".
The Belle de Jour blog was written while the Florida-born doctor was a student in London.
The award-winning blog told how she went on to work as a £300-an-hour call girl for an escort agency. Books about her experiences, The Intimate Adventures of a London Call Girl and The Further Adventures of a London Call Girl, were published in 2005 and 2006.