Chatsworth is ready for an invasion of tiny new residents

They will be set free at a secret location on the Derbyshire estate, home of the Duke and Duchess of Devonshire.

The aim is to establish an expanding population of the native species, which is struggling in the area.

The People's Trust for Endangered Species (PTES) is managing the reintroduction as part of work to boost the wild dormouse population of the UK.

The long term project is being run and funded by PTES and English Nature, with help from the Institute of Zoology (London Zoo and Whipsnade Wild Animal Park), Paignton Zoo, Royal Holloway, University of London and the Common Dormouse Captive Breeders Group.

DORMOUSE FACTS Colour - orange/yellow Body length - 60-90mm Tail length - 57-68mm Juvenile weight - 10-15g Adult weight - up to 43g Can raise one or two litters a year Usually about 4 young in a litter Longevity - five years

The Dormouse Species Recovery Programme, running for 12 years, has launched 13 reintroductions, mainly in the Midlands and North of England where the species has become locally extinct or extremely rare.

Dormouse numbers across the UK are still declining. Tony Mitchell-Jones, English Nature's mammals expert, said: "We've been delighted with the success of this project.

"It's based on some excellent science and shows very clearly that dormice can thrive in lots of woods if only they can reach them."

Jill Nelson, chief executive of PTES, said: "The Devonshire family and the staff at Chatsworth, together with our excellent team of local volunteers, have really helped us to make another important step forward in conserving this endangered and much loved mammal."

Dormice are legally protected and survive in the southern part of the UK, below a line stretching from East Anglia, through the Midlands to west Wales.