A Heathrow spokesman said:
There are some longer queues than normal in the terminals, but we have spoken to border force and they are putting on extra staff.Obviously we want to sort the issue out but not risk the integrity of the border controls.
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The film had formed part of a commemoration to the Choucair family, three generations of whom died in the fire.
John Nolan, who was found with cigarettes and two lighters, suffered burns on 65% of his body after being alight for around six minutes.
Known as Pily she died in January, seven months after the disaster, having suffered a stroke.