Danai Muhammadi, 24, from Coventry and his friend Farhad Mahmud, 35, were convicted at Maidstone Crown Court.

The pair squirted petrol through the letter box of the house using a garden spray container, leading to fire breaking out at the base of the stairs.

Melissa Crook, 20, and the couple's 15-month-old son Noah Muhammad died in the fire. Ms Crook's father, Mark, died later.

As the verdicts were read out, survivors Amanda and Bohdan Crook shook visibly and hugged each other.

As Judge Mr Justice Sweeney said that Muhammadi and Mahmud faced life behind bars, one family member shouted "good".

The judge told the jury: "There can be very few criminal cases which are as taxing for a jury than this one must have been.

"I don't suppose any of us are going to forget some aspects of the evidence we have heard about the fire."

Muhammadi's girlfriend Emma Smith, 21, was cleared of three counts of murder and two of attempted murder, but found guilty of three counts of manslaughter.

Prosecutors said the arson was a "wicked attack" which had been well planned following the breakdown of the marriage between Muhammadi and Ms Crook.