The prime minister warns the US and Iran against "escalation", as negotiations end without agreement.
"We're taking it one step at a time," Declan Holmes said, as his 66-year-old father recovers in hospital.
The birds could be reintroduced as early as next year following a £1m injection from the government.
Event organisers said it would show the "resistance" to the ban on the group was "stronger than ever".
Alnour Mohamed Ali, a 27-year-old Sudanese national, was charged with endangering life after two men and two women died.