Neighbours of Radlett house ravaged by fire said the whole street was cloaked in "a thick London fog".
The fire brigade was called to Brook Drive at about 9.40pm, when flames began leaping from the roof of the property.
Alan Besbrode, 70, and his Labrador, Sandy, dashed from his picturesque home in Brook Drive, after hearing the upstairs fire alarm sound at around 9.30pm.
The former Tesco director stood waiting on the rural gravel path, called the fire brigade and watched as the blaze worked its way through his home.
Nobody was hurt in the fire, and Mr Besbrode gave the Watford Observer access to the house to see the extent of the damage.
The a large section of the roof was completely destroyed, and every room on the first floor sustained serious damage.
Once sturdy beams have been reduced to charcoal and the walls reveal gaping holes to the outside world.
Light fittings hang redundant from what remains of the dining room ceiling, and an antique 300-year-old dining table creaks under the weight of smouldering material from the floor above.
Water from the two hour battle against the blaze still drips from the walls and soaks the carpet.
Most disturbing is the bedroom, completely blackened by smoke but seemingly undamaged by fire, and the bed, where on a normal night Alan would have slept.
Brook Drive resident, Peter Gale, who watched as firefighters tackled the inferno, said: “It was quite scary, I thought the flames were going to jump to other houses.”
Both neighbours either side of Mr Besbrode were evacuated as a safety precaution.
Describing the scene, Mr Gale added: “It was like a thick London fog. There was a horrible stench and it was so smokey.”
Steve Oakes-Monger, 53, of Park Road, who had been drinking in the Red Lion Hotel in Watling Street at the time, said fumes and smoke had made its way to the village centre almost a mile away.
This morning, investigators were still trying to find out what had caused the fire. Mr Besbrode's daughter, Emma, from Epping, said she was told it might have been an electrical fault.
Six fire engines from Borehamwood, St Albans, Garston, Watford and Rickmansworth were called to the incident, and it took more than three hours for the crews to dampen out the fire.
It proved difficult because the fire had spread into the roof space, which forced firefighters to remove tiles to get at the flames.
A plumber at the scene said: “It's shame, this was such a nice house, Alan's a really nice man and had a lot of trinkets, most of which have been burned.”
Fire investigators are currently at the scene but it is believed the blaze was started by accident.
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