Fire officials have confirmed this morning that the blaze which destroyed valuable racing cars and priceless family heirlooms in Costessey last night was started accidentally.

A collection of garages, workshops and sheds were engulfed in flames at about 3.30pm yesterday, (Wednesday) spanning two neighbouring properties on Gurney Road.

At the peak of the blaze, 43 firefighters were involved in battling the flames, but by 5pm the outbuildings were being dampened down, revealing the charred remnants of some of the property owners' most prized possessions.

This morning, a Norfolk Fire and Rescue Service spokesman said: 'The investigation into the cause of the fire continues, but we have established that it was accidental.'

The blaze destroyed a workshop on one side of the garden fence, containing �10,000 of cars owned by stock-car racer Gary LeGrice. On the other side, Norwich businessman Jim Jonas lost a 40ft shed containing a life-long collection of DIY tools, a storage shed containing his late mother's priceless collection of books, and craft equipment used by his wife Jean and daughter Amanda to run their dressmaking business.

In a garage, Mr Jonas' 30 year-old Rolls Royce Silver Spirit, part of his bridal cars business and described as his 'pride and joy', was also damaged.

After surveying the damage last night, Mr Jonas said: 'Everything has gone. I have got nothing left.

'That shed was 40ft long and full of every conceivable tool, and none of them were cheap. It was absolutely thousands of pounds worth of equipment

'The worse thing is my mother's books, which we've had since we emptied her house when she died. It was all her prized possessions and I have got nothing left of her now. There is a lot of sentimental value. Her grandmother passed them down and I thought I had no reason to bring them indoors. She absolutely loved books.

'Even worse, my wife's shed has gone as well. All these things are irreplaceable.'

It is not the first time the family has suffered such misfortune. The house, undamaged this time, was also destroyed by fire nine years earlier.

Mr Jonas heard about the blaze when a neighbour called his office on Charing Cross in central Norwich, where he runs a recruitment firm. He said he was grateful that his wife was not in the building, as she had travelled yesterday morning to visit her daughter Vicky in Yorkshire.

'She is very unwell,' he said. 'She could not have coped with this. I dare not tell her what's happened.'

The Jonas family's two other daughters – Nicola, 33, who lives in Lakenham, and Samantha, 36, from Bowthorpe – came to the house to help in the aftermath of the fire.

Samantha said: 'I don't know how to describe it. It is heart-breaking. There is a lot of money's worth that's gone up, but it is the sentimental stuff that hurts more than anything. To be honest, we're all in shock.'

Neighbour Mr LeGrice said: 'We sold off some cars and bought a new one. I was working on it, and the next thing I know the whole thing was on fire. I have lost about �10,000 of tools and �10,000 of racing cars. I don't know what else to say.'

The fire was brought under control by six emergency crews from Carrow, Sprowston and Earlham and specialist vehicles including the control unit from Wymondham and water carrier from Hethersett.

Despite initial fears of an explosion risk from gas cylinders in the densely-populated residential neighbourhood, no evacuation was needed from nearby homes as the propane containers were cooled by water jets.

Station manager Phil Berry said: 'As soon as we got here it was clear that it was a severe fire, which had spread from one building to another, leaving very little remaining of a caravan, a garage and a range of wooden sheds. With the trees involved as well, it has spread into four gardens.'