The fire that ravaged 113 Hendford Drive was “severe and rapidly developing”, the trial heard.

Forensic scientist, Greg Waite, said it was started by igniting paper soaked in petrol outside the back door.

The UPVC door melted and flames, smoke and hot gases spread quickly through the semi-detached property.

Mr Waite said the staircase acted almost like a chimney “further exacerbating the development of the fire”.

Neighbour Amir Ali said his living room lit up when the blaze started. He saw the back door of number 113 on fire and within two minutes the blaze had taken hold.

He and his wife rushed over with buckets and bowls of water but the flames were too fierce.

“It was chaos. The fire was out of control. It was extremely hot. There was nothing anyone could do,” he said in a statement read to the jury.

Firefighter Mark Stuart said he and four colleagues arrived in the first fire engine in three minutes. He put on breathing apparatus and fought his way into the burning building.

The back door was very badly burned and the house was full of smoke.

A crowd of people outside were shouting that there were children upstairs.

Mr Stuart said he took a hose reel and went upstairs. “You could not really see further than your hand in front of your face,” he said.

He went into the first bedroom where he saw a boy lying on the bed. “I picked him up and quickly passed him out of the window. He was very limp and he wasn’t breathing,” Mr Stuart said.

Another crew member found a girl’s body in another bedroom.

Asked by prosecutor Andrew Stubbs QC about the intensity of the blaze, he replied: “I have been to 40 or 50 house fires and it (the house) was as badly damaged as I’ve seen in my career.”