Richard Ratcliffe and supporters from the Free Nazanin campaign staged a demonstration in Whitehall on Saturday, during which hundreds of pebbles were painted to mark each day the mother-of-one has spent behind bars.

The protest was targeted at Foreign Secretary Boris Johnson, who promised to leave "no stone unturned" in securing Mrs Zaghari-Ratcliffe's release.

The British-Iranian dual citizen, who will spend her second Mother's Day in an Iranian prison on Sunday, is serving a five-year sentence after being convicted of spying charges in 2016.

She denies the charges and maintains she was in Iran to introduce her young daughter Gabriella to her parents.