The 82-year-old was asleep in her home when the attack happened during the early hours of Tuesday morning, and has said her life was saved by her smoke alarm.

Asking to remain anonymous for fear of reprisals, she said: "I heard someone knocking but when I looked out of the window, I couldn't see anyone so I ignored it and went back to bed. Then a while later the dogs started barking, and I heard someone shouting: 'Leg it'.

"Then the fire alarm went off, and when I ran downstairs the whole door was on fire and I couldn't see for smoke.

"I just had to keep my head on, and I ran to the kitchen and filled up a bucket of water to throw over it.

"I had to do that a couple of times before it was put out. I was very distressed, obviously, it's horrible to have been woken up that way.

"I could have died, and I think I probably would have if it wasn't for my two dogs and that fire alarm. I'm not sure I'll ever get over it."

The woman, who has lived at the address in Bellropes Square, in Ecton Brook, for the past 20 years, said she had never had a similar problem before.

But she added her neighbour's home was severely damaged about three years ago, when someone put a lit firework through the post box.

She said: "I know it's happened a couple of times before round here, and it's really nasty. The police were here for a very long time getting all the evidence though."

A spokesman for Northamptonshire Police said they were called to the property shortly after 4am on Tuesday.

He added: "At around 3.55am the householder was woken by the sound of her smoke alarm and discovered a small fire beneath the front door.

"The victim managed to extinguish the fire successfully and called the fire service who have ascertained that the fire was started deliberately.

"House-to-house inquiries have been carried out, together with a forensic examination of the scene."