The family of a British-Iranian prisoner will hold a protest close to Prime Minister Boris Johnson’s official residence on Friday – the fourth anniversary of his detention on trumped-up national security charges. The wife, daughter and son of Anoosheh Ashoori and his local MP will meet outside Downing Street with an empty chair to symbolise Mr Johnson’s failure to meet them to discuss the case of the retired engineer. Mr Ashoori, 67, was detained in 2017 and convicted of spying for Israel’s intelligence agency Mossad, following a pattern of similar sentences for dual citizens convicted on apparently spurious charges. The family will be joined by Richard Ratcliffe, the husband of charity worker Nazanin Zaghari-Ratcliffe, who is out of prison but stuck in Iran despite completing her five-year sentence. She was sentenced to a further year of imprisonment that scuppered hopes for her immediate release. Both families believe their cases are tied up with a decades-old dispute over a deal for tanks that were paid for by Iran but never delivered by Britain after the 1979 revolution. The £400 million ($554.05 million) dispute is still rumbling through the UK courts and Britain says it cannot legally repay the cash because of international sanctions. Foreign Secretary Dominic Raab told the Ashoori family last week that the UK came tantalisingly close to striking an agreement with Iran that would have secured his release around the time of unsuccessful talks in Vienna this year to revive the 2015 nuclear deal. Sherry Izadi, Mr Ashoori’s wife, said the unspecified agreement was still on the table but the change in leadership in Tehran had muddied the waters. “We got the sense that Dominic Raab really had been trying hard and was as fed up as we were,” she said. Mr Ashoori is believed to have contracted Covid-19 while in prison and is on medication for a series of health conditions. Phone calls from prisoners to relatives abroad have been stopped for months because of technical problems. “He’s hanging on there and hoping something will happen,” Ms Izadi said. “Coming up to the fourth anniversary is not going to lift his spirits.”