A sadistic arsonist who set fire to his former-partner's home as she slept inside with her two young children has been locked up.

Christopher Harrison poured petrol through the letterbox of the house in Dartford and set it alight in the early hours of September 17 last year.

Luckily, his ex and her children were woken by the smoke alarm - as were neighbours, who rushed to their aid.

They helped to put the flames out from outside the door, and the family managed to get to safety.

Obscene words were also daubed on a window, the garden gate had been damaged and items of clothing from the washing line were burnt.

When Harrison was arrested, officers found a petrol receipt in his car. CCTV also showed him buying a container and filling it up at a petrol station near the victim's house.

Now, the 36-year-old, of Langlands Drive, Dartford, has been jailed for seven-and-a-half years after pleading guilty to arson with intent to endanger life.

He was also sentenced to eight months for breaching a non-molestation order, to run concurrently, and ordered to stay away from his victims for life.

Investigating officer Detective Constable Jason Lynch said: "Harrison spared no thought for the lives of the woman and young children who were inside the house when he set alight to it and at no point has he given any motive for his actions.

"An investigation by fire experts said that was it not for the installation of a working alarm it was likely that those inside would have been seriously injured or even killed. He is clearly a very dangerous individual."