Mrs Marshall says having the charismatic star of the BBC's Two Greedy Italians pottering around in their big eat-in kitchen with stainless steel island bench is “daunting’’.

“A little bit scary, actually,’’ adds Mr Marshall, a forester who spent 20 years preparing the soil near the Monga national park for his oak and hazel trees.

"What we suspect is, if we put a bucket of truffles and a brush in front of him, he will be quite happy because he loves his mushrooms,'' Mr Marshall said.

But as they soak their shaved black truffles into creamy soup, with their golden retriever/kelpie Sal, the quiet champion of truffle dogs, and her understudy, Shadow, a Labrador/dachshund at their feet, their confidence grows.

In rising earthy aromas of their truffles, they tick off the attributes of their surroundings which have lifted the capital region to the top of the Australian truffle industry, a fact marked by the coming festival and afterwards its patron Carluccio, the silver-haired author and doyen of celebrity chefs.

"His cuisine is very achievable because he is all about the natural flavours and honesty of the ingredients. That makes his recipes very achievable,’’ Mrs Marshall said.

Mr Marshall will give their guest a pile of sticks pruned from his hazel trees and his second-best pocket knife so he can add to his walking sticks which are his special hobby.

''He loves dogs and our dogs are very lovable,'' Mr Marshall said.

The eight-week truffle festival, which co-ordinator Lana Mitchell says is becoming the Floriade of Canberra's winter, begins on June 14, with 60 participating venues serving cool climate produce.

One of seven participating farms in the festival, the Marshalls established truffles to inoculate trees, accidently spearheading farm tourism that is flourishing across the Southern Tablelands with cool climate grapes, honey, goats and olives serving a ready market in Canberra, garnished with international chefs.

Following old forestry books Mr Marshall finished up with a late-18th century French forest, exactly what truffles grow in.

When they invited visitors on a truffle hunt some people pulled out iPhones to tell friends in Sydney to book for the next one.

"Suddenly it just exploded,’’ Mr Marshall said. ''Honestly, we just don't have as a family enough time or resources for as many hunts as people would like. I am trying to scale back on them.''

He says native truffles are as crucial to our ecosystem as French and Italian truffles are for a winter festival.

Bettongs, potoroo and bandicoots scraped up truffles and turned over soil, burying an almighty fuel load, until foxes and cats wiped them out.

''Two hundred years ago there would have been a dozen bettongs per hectare all burrowing and burying the eucalyptus debris, now it is all on the surface,'' the forester said.

''My thinking is, insurance companies which must insure against fire should be investing some of their money in wiping out foxes and cats so the small marsupials can get back to the work. Quite seriously.''