IT was the legal equivalent of pistols at dawn as a blue-blooded fall-out of epic proportions reached the courts yesterday.

The stepmother of a Scottish earl is demanding that a judge throw him out of the fastness of Cawdor Castle. The aristocratic argument features Angelika Ilona, the dowager Countess Cawdor, and Colin Robert Vaughan Campbell, the 7th Earl Cawdor and 25th Thane.

''The present dispute arises out of a raft of disagreements between a stepmother and the son of her husband's first marriage,'' explained Sir Crispin Agnew, of Lochnaw QC, counsel for the earl.

Lord Osborne heard claims that the earl had jeopardised the castle's priceless collection of art and furniture by switching off its sophisticated alarm system.

The earl also lit a fire in the yellow drawing-room, failing to realise that the chimney had been blocked. The result was that smoke billowed into the room, causing a call-out by fire tenders and the police.

The dowager countess asked the court for an interim order awarding her possession of the castle, near Nairn.

Craig Sandison, her counsel, explained that she was the wife of the 6th earl who died in 1993, leaving the castle to his widow, and the castle now operates as a tourist attraction.

The business was run by Cawdor Castle Tourism under a lease granted by the late earl and, until recently, the dowager countess had been a director along with her stepson. She resigned last month because she felt she could longer work with the earl. Macbeth was the most famous Thane of Cawdor.

The castle was open to the public during the tourist season and, during the close season, Lady Cawdor lived in private apartments in Cawdor Castle. Until last Friday, the earl lived in an entirely separate property not far from Cawdor.

While the dowager countess was holidaying in the USA, she received a phone call telling her that the present earl and his family had moved into the castle on November 1.

The earl had issued a fax claiming to be under a duty to occupy the castle in terms of the lease for security purposes and proposing to remain there until the expiry of the lease in May 2003.

The countess immediately instructed an action in the Court of Session, seeking the removal of the earl and countess on the basis that they had no right to occupy the castle and has now also given notice that she regards the lease as having been forfeited.

Mr Sandison explained that the dowager countess had installed an intruder alarm system and there was an obligation under the lease to maintain and operate the existing security equipment.

The dowager countess had also been denied access to the castle when she arrived to collect personal papers, clothing and other personal items.

Sir Crispin argued that after the dowager countess resigned as a director of the tourism company, she was no longer entitled to stay in the castle in terms of the lease.

He alleged: ''I am told she resigned as a director because certain questions were put to her in regard to the accounting of the company. Rather than answer, she resigned.''

Mr Sandison countered by describing this claim against his client as ''little more than a slur'' which was ''vehemently and utterly denied''.

After hearing four-and-a half hours of legal argument, Lord Osborne went home to ponder his decision and will issue a ruling tomorrow.

Dramatis Personae

The Dowager Lady Cawdor The former Countess Angelika Lazansky, widow of Count Prokop Lazanski von Bulowa of Chieska, Bohemia and Salisbury, Rhodesia, married the sixth Earl Cawdor in 1979 after his 22-year marriage to his first wife, Cathryn, was dissolved. A friend of Princess Michael of Kent and formerly of the Prince of Wales, she has been accused by members of the Cawdor family of making them unwelcome at the ancestral home. The ''secret will'' of the late sixth earl, who died in 1993, resulted in his son deriving his income from the estate's 60 sq mile grouse moor, while the dowager takes her income from the castle, open to the public during the summer, and its adjoining land.

She was described by her stepdaughter, Lady Campbell, in an article in Harpers and Queen magazine as ''Lady Macbeth Mk II'', ''Diabolika'' and ''a stepmother from central casting''. An organic farmer for more than 20 years and member of Friends of the Earth, she has called for the immediate scrapping of genetically modified (GM) crop trials in Scotland.

Lord Cawdor - 25th Thane and seventh Earl of Cawdor Educated at Eton and Oxford, Colin Robert Vaughan Campbell, 38, trained as an architect and practised in New York for seven years before marrying and returning to Cawdor. He fell out with his stepmother over plans to sow genetically modified crops on the estate. He and his young family were apparently ousted from his ancestral home and now live in what is described as ''a croft'' on the estate. The estate and Cawdor Castle are estimated to be worth (pounds) 20m. He has three children - two daughters and a son and heir, Viscount Emlyn.

Lady Isabella Cawdor Born Lady Isabella Stanhope and educated for the first 12 years of her life in Limerick, she is the youngest of eight children of Lord Harrington.

After boarding school in England and art college she worked for the late Bill Gibb, the fashion designer, before backpacking around South America.

Back in London, she worked as a fashion assistant on Vogue then moved to Elle before deciding to go freelance as a stylist. She was introduced to her husband-to-be by his sister, her friend, fashion journalist Laura Campbell. They married in 1994 and moved to Cawdor.

Lady Isabella took over the running of Drynachan Lodge, a sporting retreat on the estate, and three other cottages used as a country retreat for up-market holidaymakers. She also set up a successful location and production business.