A short walk onto the scorched earth revealed just how devastating the fire had been for the wildlife which depends on it.

Jez Martin, nature conservation officer for Borough of Poole picked up a blackened slow worm.

“It’s immature, half-grown,” he said. “Without much effort I could find some more dead ones.”

And he has concerns for a Dartford warbler he knew was nesting close to the site of the fire. “Even if its nest is still intact its food source is gone - all the insects and spiders.”

One nest here and there was significant when there are probably under 1,000 in the whole country, he said.

While the arson attack has affected two hectares of the 280 hectare protected heathland, it represents the loss of mature gorse and heather which will take well over 15 years to recover.

“What are these people thinking who do this? It’s a risk to themselves, to the firefighters here with their equipment, a risk to walkers and cyclists,” he said.

Jez was first on the scene on Tuesday night, seeing light as he was moth-trapping on the heath. “I saw the glow and thought it was street lights. A few minutes later I realised it was a fire. I was the first person here by half-a-minute before the first pump turned up.”

The frequency of arson attacks led a few years ago to an education programme, more fire breaks and hydrants installed on the heath.

“Canford Heath is one of Dorset fire brigades best customers for fires – unfortunately,” he said. “Because of that we have taken measures to try and manage the risk as much as we can.

“It helps when a fire is started. But it’s best not to have a fire in the first place.” And while the numbers of fires had fallen, some had been started by adults, he said.

A devastating deliberate fire in 2006 resulted in the loss of 34-45 hectares of prime heathland, which will still take many more years to recover.

He warned against carelessly discarding cigarettes in the tinder dry conditions and urged people to ensure they properly extinguished barbecues, particularly on beaches fringed by heath.

The most devastating fire of recent times was in June 2011 when an area of 200 acres of Upton Heath was destroyed in an arson attack, killing rare reptiles and birds and injuring four firefighters.

More recently a wildfire destroyed one hectare of heath, gorse and trees at Studland on July 9, which was fought by around 60 fire crew and resulted in one being taken to hospital suffering from the effects of heat.

Ham Common at Hamworthy also suffered a recent fire, with around 30 fire fighters, four crews and four Land Rovers needed to fight the flames on July 11.