Mocking an injunction banning her from speaking about the family battle, Penny Allen and her fiance, Ismay Tremain, both covered their mouths with scarves. He sported a makeshift nappy.
The pair were appearing before the court for a hearing of an injunction, first granted to Mr McEwan on Friday, banning them from disclosing information about court proceedings in England and France as well as the writer's life.
Mrs Allen was defiant as she arrived at the High Court. Last week she sparked a nationwide search when she disappeared in France with the youngest of their two sons. He was later returned to his father.
"I am saying I had been silenced for five years since I left my husband," said the spiritualist healer, adding: "Today he's trying to take away my freedom of speech."
In a further act of ridicule, Mr Tremain - a mineralogist christened Steve Brown - claimed to have changed his name again by to Ian Russell McEwan and brandished a briefcase bearing the message "My latest novel is entitled The Destruction of Penny Allen and Ismay Tremain".
The Booker prize-winning novelist, who has maintained a dignified silence about the feud, stayed away from the hearing.
Mrs Allen, 51, and her fiance attended court briefly. They walked out without waiting to hear the judge, Mr Justice Charles, extend the injunction until tomorrow for a fuller hearing. As they left the court, Mr Tremain immediately ignored the order and launched a vitriolic attack on the novelist.
"She loves those kids," he said of his partner. It was the latest instalment of a bitter public row that started when the couple's 13-year marriage broke up in 1995.
An arrangement for shared custody of their sons, now aged 13 and 15, dissolved when Mrs Allen moved to Brittany to set up a retreat. In March Mr McEwan, 51, was granted sole custody of both children.
Under the agreement the boys' mother was to be allowed access visits with the children travelling to the rundown farmhouse she shares with Mr Tremain in Bulat-Pestvivien.
Last Thursday Mrs Allen disappeared from the court in Guingamp near her home before waiting to hear an order to return her son to his father.