The family of Nazanin Zaghari-Ratcliffe delivered flowers to the Iranian embassy in London to mark another Mothering Sunday she is spending in prison.
Ms Zaghari-Ratcliffe, 40, was jailed for five years in 2016 after being arrested as she prepared to return to the UK with her daughter after visiting family.
The charity worker’s supporters say she is being treated as a political pawn amid deteriorating relations between London and Tehran.
“Enough is enough,” her husband Richard Ratcliffe told the BBC. “We really do need to find a way out of this.”
Their daughter Gabriella, four, remains in Iran where she visits her mother every week but has not seen her father since her mother was arrested. Mr Ratcliffe has been unable to secure a visa to travel to Iran.