Four robbers who broke into the plush country home of a wealthy businessman at night armed with a sword, sledgehammer and handgun have been jailed for a total of more than 30 years.

The masked gang smashed their way into Dunmore in Bough Beech Road, Four Elms, Edenbridge, and threatened the wife of Colin Graves - who founded the Costcutter chain of convenience stores - and stole £220,000 of jewellery.

Ringleader David Milner, 34, was sentenced to 10 years, Zak Price, 23, to eight years and three months, Jack Menzies, 22, to seven-and-a-half years and 22-year-old Aaron Wall to four years and eight months.

Wall, of Hill View, Basted, Borough Hill, Sevenoaks, and Price, of Goldsmid Road, Tonbridge, admitted robbery and possessing a firearm with intent to commit a robbery.

Milner, of Beech Road, Biggin Hill, and Menzies, of Parkview Road, Eltham, south east London, admitted robbery but denied the firearm charge.

They were both convicted after a trial in which Mr Graves' wife Sharon was forced to relive her nightmare in the witness box.

She was praised by Judge Jeremy Carey for her bravery.

Dominic Connolly, prosecuting, said after Milner, Menzies and Price entered the house at around 2am on March 19 and helped themselves to the jewellery and other property they were driven away in a 4x4 car by Wall.

Mrs Graves, 53, was in bed at the gated property, which has tennis courts, stables and an indoor swimming pool. The couple's daughter Francesca, 16, was asleep in the house. Mr Graves was in Barbados at the time.

Mrs Graves was awoken by the bedroom door being forced open and three masked men bursting in.

Mr Connolly said Milner was waving around a sword and carrying what looked like a mallet. Price had a gun. Menzies was not armed.

Price pointed the gun at Mrs Graves and told her to lie down on the upstairs landing. She took the quilt from the bed and did as she was told.

She described Price continuing to point the gun at her with an outstretched arm. Several times he told the three others: "Thirty seconds."

Mrs Graves pleaded with him not to hurt her and he said he would not.

Milner and Menzies took jewellery from the safe. "It seems they knew where to look," said Mr Connolly. "They didn't go to any other places.

"They seemed to be able to operate the rather complicated lighting system.

"They managed to get past the coded entrance gate. Mrs Graves was instructed to lie face down and count to 30.

"As she did that, the three men ran from the property. When she thought they had gone she telephoned the police."

Police saw the getaway car speeding away and followed, but it was decided not to continue because of the firearm.

DC Don Share, from the Kent and Essex Serious Crime Directorate, said: "It is difficult to imagine the fear that the mother and her daughter felt during this crime and that has been reflected within the sentence.

"Anyone who possesses a firearm should expect to go to prison for a long time; even more so should they commit a violent robbery such as this.

"Now the case is concluded it is time for the victims to move on in their lives, safe in the knowledge that these men are in prison for many years to come."