Estranged dad, Richard Ratcliffe who has been separated from daughter Gabriella for over 66 days, plans to sing Happy Birthday to her via Skype at a teddy bears' picnic tomorrow (June 10).
Richard’s wife Nazanin Zaghari-Ratcliffe, a British-Iranian national - has been held in Iran without charge since April 3.
She was separated from Gabriella after being stopped at Imam Khomeini airport in Tehran as they tried to return to the UK from a family holiday.
The toddler who is being looked after by her grandparents had her British passport confiscated by the Iranian authorities and Nazanin is being detained 621 miles (1,000km) away from her in Kerman Prison.
Richard's petition on Change.org calling for his wife's release currently has more than 750,000 signatures. He presented his petition to Number 10 Downing Street on May 19 but it still collecting signatures as the campaign continues.
Tomorrow, Richard will be joined by friends, family and his MP Tulip Siddiq, to hold a birthday picnic in Hyde Park to celebrate Gabriella’s birthday.
The Iranian Embassy has confirmed it has received birthday cards addressed to Gabriella from supporters of Richard’s campaign in recent weeks.
Richard will also attempt to present a card to the Embassy at 1pm and ask that they pass it on to his daughter.
He said: ‘I am overwhelmed by the public outcry about my baby daughter's birthday. I am grateful that she is with her loving Iranian grandparents but, nonetheless, I want her and her mother together and back home with me as soon as possible.
‘It has been really moving for all my family here to see the kindness of people across the country connecting with our story, making cards for Gabriella with their own children or grandchildren, and doing something to make Gabriella's world a better place.
‘In my bones, I feel it is that kindness that will in the end bring them home.’
For more about this campaign go to change.org/freenazanin or email email@example.com.