One of Britain's biggest landowners, the Duke of Buccleuch, has died after a short illness. He was 83.

His family said he died at his Bowhill home in the Borders.

He led a long and colourful life which saw him serve his country in the Second World War and as a Conservative MP where he roundly defeated the late Robin Cook in Mr Cook's first attempt to enter the House of Commons in 1970.

Aside from his extra-curricular activities, like many of his forebears, he ensured that his extensive family estates, spread throughout the south of Scotland and Northamptonshire, remained in the vanguard of innovative and energetic land management.

As recently as 2005, the duke was believed to be Britain's biggest private landowner, owning 270,000 acres, mostly in the Borders.

The Sunday Times Rich List estimated his wealth at £85m. The Buccleuch Estates alone, which he chaired, were estimated to be worth £71m. He also had an art collection worth an estimated £400m.

The same year it was reported that Buccleuch Estates made a £3.6m loss in 2004 despite receiving £790,000 in European and government farm subsidies and grants.

The duke hit the headlines in August 2003 when he became the victim of Britain's biggest art heist. Two men stole a Leonardo da Vinci painting, Madonna With The Yarnwinder, from Drumlanrig Castle in Dumfries and Galloway. The painting had been in his family for more than 250 years.

The case remains unsolved. Last year the theft moved up to seventh on the FBI's art crime most wanted list and its image is prominently displayed on the logo of its art crime unit.

Born Walter John Montagu Douglas Scott in 1923, the oldest son of the eighth duke - whom he succeeded in 1973 - was educated at Eton and Oxford.

In 1942 he joined the Royal Navy as an ordinary seaman, was commissioned the following year and saw action including U-boat sinkings.

After the war he studied agriculture and forestry at Oxford, and became director of the Buccleuch Estates in 1949. He married Jane McNeill in 1953 at a wedding attended by the Queen, the Duke of Edinburgh, and most of the royal family at St Giles' Cathedral in Edinburgh.

The couple lived at Eildon Hall, Melrose, where he was brought up, and their first son Richard, now the Earl of Dalkeith, was born in 1954.

Three years later the duke became a Tory councillor in Roxburghshire, and later served as Tory MP for North Edinburgh for 13 years.

His political career was severely curtailed in 1971 when he broke his back in a hunting accident. Although confined to a wheelchair his disability did not reduce his energy as a landowning entrepreneur and spokesman.

In 2002 he attacked proposals for land reform in Scotland, saying these would "penalise rural families as viciously as a foul disease". The same year he also urged pro-hunting supporters to use every legal means to challenge the hunting ban proposed for Scotland.

He also became involved with many charities following his accident. Lord Steel, the former Liberal Democrat leader and a near neighbour of the duke, was among those who paid tribute yesterday.

He said: "His was a long and distinguished public life of which his wife Jane and his four children must be immensely proud. Our hearts go out to them. His personal courage, vigour and humour after he was confined to a wheelchair was remarkable."

Lord James Douglas-Hamilton, the former Tory minister who also knew the duke well, said: "This is very sad news. Johnnie was extremely courageous after his devastating accident and was determined to play a full role in Scotland and live life to the full."

A spokesman for the National Farmers' Union in Scotland said the duke was "an iconic figure" within rural Scotland. The estates The Duke of Buccleuch lived mainly at his 46,000-acre Bowhill estate near Selkirk. Newark Castle was once used as a hunting lodge by the kings of Scotland. His other main residence was the 17th century Drumlanrig Castle, the largest of the Buccleuch estates, covering 111,000 acres. It contains one of the UK's finest art collections, including masterpieces by Leonardo, Rembrandt, and Holbein. His other estates included the 94,000-acre Langholm estates, the 2500-acre Dalkeith estate, and the 11,000-acre Boughton estate in Northamptonshire. Buccleuch Estates employs about 1000 people. While its heart remains in the countryside, its activities span a broad spectrum including commercial property investment and development, meat and speciality foods, livestock haulage, and farming.