A drug trafficker organised the smuggling of heroin into Scotland with tool boxes attached to the underside of a lorry by magnets.

Cameron McFarlane was jailed for nine years for tracking the 20kg of illegal cargo as the HGV made its way from the Netherlands to Millar International Freight at Bandeath Industrail Estate, Throsk, Stirlingshire.

Unknown to McFarlane, he had become a target for a police operation aimed at cracking down on a serious, organised crime gang.

He was under surveillance and was seen flying out of Glasgow to Amsterdam where the Dutch authorities also monitored his activities.

The lorry was seen returning to the yard of the firm where McFarlane had previously worked and a search of the vehicle found the drugs attached to its chassis.

The 20kg of heroin was estimated to be worth £600,000.

Lord Pentland told the 57-year-old at the High Court in Edinburgh: "You pled guilty to an extremely serious charge of being concerned in the supply of more than half a million pounds of high quality heroin."

The judge said McFarlane had provided guidance and direction to others to allow the drugs to be concealed for the smuggling operation.

"You made elaborate arrangements to monitor the movement of this vehicle by placing spyware on it," he said.

Lord Pentland said McFarlane's plan was to retrieve the heroin from the lorry at "a convenient time".

McFarlane has twice previously been jailed at the High Court for trafficking in Class A drugs and at the time of his latest crime had been released early from an open prison.

Lord Pentland told him: "It is especially concerning the present offence was committed while you were on licence in the community.

"You grossly breached the trust placed in you."

The judge said: "I conclude you are a hardened drug dealer with no respect for the law."

McFarlane, a prisoner at Low Moss jail, near Glasgow, admitted being concerned in the supply of heroin between September 25 and 28 last year at Bandeath industrial estate, Hull and Amsterdam.

Intelligence was received over McFarlane's interest in Millar International Freight at the Bandeath estate and authority was granted to put him under surveillance.

He was seen at the departure lounge at Glasgow airport in September 25 and after flying into Amsterdam and became the subject of surveillance by the Dutch.

McFarlane collected a Mercedes Benz hire car and drove to a hotel and was seen carrying two tool boxes.

After his return to Scotland, surveillance continued and police learnt that he had "a criminal interest" in HGVs registered to Millar International where he had worked many years before, the court heard.

He was stopped on September 28 in a Land Rover Discovery and a note was found referring to the address of a KFC restaurant in Amsterdam which he later explained was in the area where the drugs were brought to him.

Police on the M74 saw a Millar International HGV heading north on the same day.

Mr McGuire said: "The managing director of Millar International authorised the police to search any vehicles within their yard at the Bandeath industrial estate."

Half an hour later, the lorry that had been seen on the motorway heading north pulled into the firm's premises and officers saw two toolboxes secured to its trailer.

Inside, they found the heroin in packages bearing the logo of the Lotus car firm. McFarlane revealed he had used a tablet to monitor trackers placed on the lorry and police found a black box containing such a device attached to an air tank.

A second lorry that returned was also found to have a tracking device placed on it used to monitor its progress.

During an interview, McFarlane said that in the Netherlands he had seen the drugs packages which were handed over at a meeting where he instructed others what to do.

Mr McGuire said: "The accused stated that he returned to Scotland on September 27 and knew that the vehicle would be coming back and that it would be a case of simply retrieving the cargo."

The Crown served papers for a proceeds of crime action on McFarlane seeking to seize any illegal profits.

McFarlane, who set up a chauffeur and valeting business, was also given a serious crime prevention order which includes limiting his access to phones and other devices on release.