I thought Emily Thornberry made a very good appeal to the Iranians in Parlisment yesterday.
She reminded them of how international teams of rescue experts, including British firemen and police (I think) had rallied round to help in Iran in 1990 when there were major earthquakes and suggested that as we rushed to their aid, when it was needed, regardless of political problems, now faced with a potentially global pandemic they should now release, Nazanin (and other foreign nationals in their prisons), regardless of political issues.
It will win the Iranians, international good will compared wit the opprobrium that will engulf them, if any of those foreign prisoners die of the Corona virus while in their prisons.