LONDON (Reuters) – Supporters of Iranian-British aid worker Nazanin Zaghari-Ratcliffe, who is jailed in Iran, sang “homecoming” carols outside Prime Minister Theresa May’s Downing Street offices on Tuesday evening.

Her husband Richard and opposition Labour party foreign affairs spokeswoman Emily Thornberry joined singers at the vigil who were also pressing for the return of Briton Andy Tsege, a father of three who is being held in Ethiopia.

Zaghari-Ratcliffe, 38, a project manager with the Thomson Reuters Foundation, was arrested in Iran 19 months ago and sentenced to five years in jail after a court convicted her of plotting to overthrow the clerical establishment. She denies the charges.

Her supporters have also sent a letter to Iranian Supreme Leader Ayatollah Ali Khamenei urging him to free Zaghari-Ratcliffe and allow her to be reunited with her husband and their three-year-old daughter Gabriella.

May’s government is under intense pressure to secure Zaghari-Ratcliffe’s release, in part because of remarks Foreign Secretary Boris Johnson made last month that Iran said justified her conviction.

Johnson, who has since said he was “wrong” for saying that Zaghari-Ratcliffe was in Iran in a professional capacity “training journalists”, is due to visit the Islamic Republic soon but no date has been announced.

Zaghari-Ratcliffe is expected to appear in court in Iran on Dec. 10, her husband has said.

The Thomson Reuters Foundation is a charity organisation that is independent of Thomson Reuters and operates independently of Reuters News.