Investigators are preparing to trawl through rubble and blackened timbers to search for the bodies of a millionaire and his family as the final embers from the blaze at their home are damped down.

Forensic teams have been prevented from entering the £1.2 million Georgian mansion of Christopher Foster, his wife Jillian and their teenage daughter Kirsty, because of safety fears after the building was gutted by fire in the early hours of Tuesday morning. The family are yet to be traced.

Superintendent Gary Higgins, from West Mercia Constabulary, said every possible line of inquiry to find the family was being followed up.

He said: “Until we can enter the property, we do not know whether the family was inside at the time of the fire, which we believe was started deliberately.

“A lot of work has been done by the fire service overnight to damp it down and reduce the temperature enough for work to stabilise the structure to begin and make it safe to enter.

“Once it has been deemed safe, which we are hoping will be either this evening or tomorrow, specialist search teams and forensic experts will go in.”

The suspected arson attack razed parts of the building to the ground but a charred shell remains of the main house and structural engineers have been assessing the building today before teams of investigators are allowed to enter. CCTV from parts of the building search teams are able to reach has been recovered.

Mr Foster, 50, who once claimed to be the victim of a blackmail plot, his wife, Jillian, 48, and daughter, Kirsty, 15 have not been seen since the fire at Osbaston House broke out in the early hours of Tuesday morning. They are thought to have died in the blaze at Maesbrook near Oswestry, Shropshire and up to 80 police officers are involved in the investigation into the fire.

It was immediately clear to the emergency services that they were arriving at a crime scene. One witness described how the family’s two dogs had been shot dead in their kennels and then dragged into the house, leaving a bloody trail. Two horses in the stable, and another in a barn, had also been shot dead and left for the fire to consume.

Inside the house, already bristling with security protection, there was said to be evidence of a hurried attempt to build a barricade inside the front door. There were also unconfirmed reports that numerous spent cartridges had been found.

A horse box with its tyres let down had been left outside the imposing security gates, hampering the work of fire crews arriving at the scene along the country road.

It is believed that the arsonist had laid fires in the stables and kennels as well as the main house. The burnt rafters had fallen into the basement in the fierce heat leaving only the walls standing, and in the garage the couple’s four cars, including two Porsches, were reduced to blackened shells. West Mercia Police began an investigation but a search of the property was delayed because the structure was deemed to be unsafe.

The Foster family were all photographed together enjoying a barbecue at a friend’s house on Bank Holiday Monday — just hours before their home was burned to the ground.

Residents in the village of Maesbrook, near Oswestry, spoke of a happy family but one that was rarely seen and seldom entered into community activities. Mr Foster was described as a friendly presence behind the wheel of his black Range Rover while his wife was often seen exercising the horses. Kirsty was a pupil at Ellesmere College. But behind the façade, cracks had begun to appear. Mr Foster was managing director of Ulva Ltd, a Telford company that supplied insulation for oil rigs and which went into liquidation last year.

The company imploded in a series of protracted legal wrangles that culminated in the Court of Appeal branding him “bereft of the basic instincts of commercial morality”.

Although Mr Foster is believed to have made millions from Ulva, by last year the company was running into serious financial trouble. After losing a court case it owed almost £1 million to a supplier, DRC Distribution, as well as more than £800,000 to the taxman. Mr Foster was under threat of prosecution for “irregularities”.

Fearing ruin, Mr Foster then began transferring assets out of his business, of which his wife was company secretary, in what Lord Justice Rimer described as “an asset-stripping exercise directed at enabling him to carry on its business through another company with a similar name”.

In October 2006 Mr Foster had been dragged into a seedy court case after accusing two men of trying to blackmail him for £100,000 when a land deal in Cyprus fell through. The men were cleared at Shrewsbury Crown Court of making an unwarranted demand with menaces, but one was convicted of intent to pervert the course of justice and given a suspended prison sentence.

Mr Foster retreated to his country backwater, turning the house into a “fortress” with gates and CCTV.

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