A mysterious death, dark conspiracies and the suspicions tearing one of Britain's most distinguished families apart are revealed by RICHARD KAY

Even in the most bitterly divided of families, death tends to bring people back together. Hostilities are suspended and sorrows shared.

When the 8th Marquess of Ailesbury was laid to rest in June, the atmosphere at St Katharine’s church, deep in Wiltshire’s Forest, the ancient woodland of which his family have been custodians for centuries, crackled with tension.

For the holder of such a distinguished aristocratic title, Michael Brudenell-Bruce was a diffident and modest figure. Although naturally proud that he could trace his forebears back to the royalist cause in the English Civil War, in recent years he often liked to style himself simply ‘Mr Bruce’.

None of his three marriages had brought him lasting happiness and he was estranged from some of his children. But for almost four decades he shared his life with a woman to whom he was devoted.

Teresa Marshall de Paoli, a vivacious former fashion model, believed she made him happy and steadfastly looked after him as dementia began erasing his other interests and clouding his memory.

Despite not marrying, they lived together for 37 years, just one year less than all of his marriages put together.

Lord Ailesbury’s passing at 98 was hardly unexpected, but the manner of his death, falling from an open first floor window in May, has triggered all kinds of dark conspiracies.

Friends believe it happened as he leant out of the bedroom window while trying to free the family’s ginger cat Honeybun and lost his balance tumbling on to the paved garden 10 feet below, striking his head.

Miss Marshall de Paoli described it as ‘a freak accident’. His son David, 71, formerly the Earl of Cardigan and now the 9th Marquess – who it has emerged is contesting his father’s will, which was changed two years ago – has, however, expressed reservations at this explanation.

‘The sadness is she and he were alone in the building and we will never know,’ he pointedly told The Mail on Sunday.

An inquest into Lord Ailesbury’s death which opened at West London Coroner’s Court this month heard that his father died from multiple injuries. It was adjourned until November when a two-day hearing will take place.

His passing has not just opened old wounds of family acrimony and recrimination but has shone a spotlight on the burden of carrying such a famous name.

It has been that way ever since a distant kinsman, Lord Cardigan, led the ill-fated Charge of the Light Brigade into the infamous ‘Valley of Death’ during the Crimean war with Russia in 1854.

More recently, the name flared into the headlines when the lingerie model Florence Brudenell-Bruce – known as Flee and from another branch of the family – was briefly linked romantically to Prince Harry.

And in 2012 Ailesbury’s musician granddaughter Lady Catherine, better known as the singer Bo Bruce, was the break-out star of The Voice, the BBC talent show on which she was runner-up.

But for Michael Brudenell-Bruce, his title weighed heavily, and his death falling from a window is a poignant and tragic echo from the past.

In 1937, when he was 11 and a schoolboy in Kent, his mother Joan dramatically plunged to her death from the seventh floor of the Savoy Hotel. A court was told that she was of ‘unsound mind’ when she took her life.

Two days earlier, she had booked a suite, arriving, it was noted at the time, with little luggage and without a ladies’ maid. On the day she died, she had changed into evening dress and ordered dinner to be served in her room. Her body was found on the street below, her meal barely touched.

What drove a young mother of two to take her life was not divulged and her name was rarely mentioned again at the family home. ‘It was a forbidden subject,’ Brudenell-Bruce later old one of his grandchildren.

There seems little doubt that the trauma of this huge loss overshadowed Lord Ailesbury’s life.

Marriage was no consolation. Like his father, Michael had three wives. His first in 1952 was Edwina Wills, a debutante and heiress to the Wills tobacco fortune. After her father Sir Ernest de Winton-Wills opposed the marriage because he considered that at 19 his daughter was too young, the headstrong couple eloped to France and were wed in Menton, on the French Riviera.

They had three children, David, Lady Sylvia and Lady Carina, but the marriage did not last.

In 1961, Michael – then using the courtesy title Viscount Savernake – was granted a divorce on the grounds of his wife’s adultery with the celebrated actor James Robertson Justice – bearded star of the Doctor films and close friend of Prince Philip.

Undeterred, he married again in 1963 to Juliet Lethbridge with whom he had two further daughters, Lady Louise and Lady Kathryn. It too ended in divorce 11 years later when both he and his wife admitted adultery.

One further marriage - to divorcee Caroline Romilly - formally ended in 1992.

By then he had already met Teresa, who had a far more glamorous, but less complicated romantic past. She has never married.

Ten years his junior, they met at the Derby in 1987 when both had been invited to the same bibulous lunch party.

A successful international model and regularly in the gossip columns in the 1950s and ‘60s, Teresa had come close to marriage only once – to the roguish ITN reporter Reginald Bosanquet, later the network’s most celebrated newsreader and known affectionately to viewers as ‘Reggie Booze-at-Ten’.

Bosanquet was separated from his then wife when he proposed. They split up not long afterwards but Teresa, who says she also fell pregnant by the broadcaster, still has a telegram sent from Paris by her former lover. It reads: ‘You are very much loved, missed and wanted.’ It is signed simply ‘Reggie’ and dated February 3, 1961.

At the time, Teresa was known as Terry and in demand as a model for Vidal Sassoon, Mary Quant and the French designers Pierre Balmain and Ted Lapidus. For a while she lived in a Holland Park flat above the actor Denholm Elliott, who became a fast friend.

It was through another boyfriend, the American actor Brad Dexter – one of the stars of The Magnificent Seven – that she met Frank Sinatra, whom she recalled bridling whenever his Italian ancestry was brought up.

‘If anyone calls me a “w*p”, I would break their legs,’ she remembered Sinatra telling her. ‘I said I was proud of my mother’s Italian heritage, and told him how great it was to be a “w*p” because Italy produced Michelangelo and the Renaissance.’

In later years, she had flamboyantly adopted her mother’s maiden name de Paoli. She says she liked Sinatra, who at the time was divorced from his second wife Ava Gardner, but they never dated.

Her most persistent admirer, she claims, was the hellraising Hollywood star Errol Flynn. ‘He kept asking me out but I turned him down. I was only 19, he was in his 40s. His son Sean, who was very sweet and very good looking, said no one ever turned his dad down. He said Lana Turner hadn’t and nor had Rita Hayworth, but I did.

‘I remember Sean [Flynn] telling me he would never be like his father. It was true, he took me out and didn’t make a pass at me or even have a drink.’

Before meeting Lord Ailesbury, Teresa’s longest relationship was the three years she says she spent with globetrotting TV figure Alan Whicker. ‘Alan was fabulous company, we had great fun,’ she says.

Family photograph albums and scrapbooks are crammed with snapshots of her cover-girl days and mementos of her romances include pictures of her with Bosanquet and relaxing in Whicker’s Regent’s Park home.

By the time she met the marquess her modelling days were over and she says she was charmed by the quietly spoken and retiring Old Etonian and former Royal Horse Guards officer, who had left the Army for a successful career as a City stockbroker.

As a younger man, Brudenell-Bruce had also run with the wild set – his friends included John Bingham, later the Earl of Lucan, the runaway peer who vanished after the murder of his children’s nanny in 1974.

Both were gamblers – Lucan at the gaming tables, Ailesbury on the track. At one stage he owned racehorses and weekends were spent following their fortunes. According to family lore, he asked Lucan to be a godfather to one of his children.

Indeed, he later told family members that he was convinced that his old friend had not taken his life, as was suspected, but was in fact alive and living in Goa, India.

He and Teresa, meanwhile, were soon firmly attached and she was regarded by some of his children as a much-loved stepmother. By then she had written a novel, A Rich Alliance, though the title of this upper class saga was a far cry from their own modest circumstances. Until 2008 they lived in what Ailesbury described as a ‘woodland cottage’ on the Savernake estate.

They then moved to Shepherd’s Bush in West London, and settled in a small terraced house owned by Teresa.

There was by then no great family fortune – Ailesbury’s father had moved to tax-friendly Jersey to preserve his finances – and Michael had had three divorces. He also complained that their Savernake Forest dwelling, where they were often cut off in winter, had become ‘too remote at my age’.

In any case, by 1987 he had no real interest in rural affairs and had handed over his position as hereditary warden of the forest to his son David, who had assumed the style Lord Cardigan in 1974 on the death of his grandfather.

After succeeding to the marquessate, Ailesbury took up his seat in the House of Lords as a crossbencher but did not make his maiden speech until 1979.

His father, however, an eccentric figure, cast a long shadow. A pioneering airman and motoring enthusiast, he made headlines in 1940 after being listed as a casualty by the War Office, only for it to emerge that he had escaped from his German captors who had taken him prisoner as they pursued British troops to Dunkirk.

In a book published after the War, he described how he had leapt from a German lorry and made a thrilling escape through occupied France to Spain, at one stage accepting a lift in a Nazi officer’s staff car.

Just as Michael had with his own first marriage eloping to France, his parents too caused a society sensation with a secret wedding in Brentford, West London, because his father Cedric was underage. Newspapers later described his mother Joan Salter as ‘the boy earl’s bride’.

The daughter of an Isle of Wight architect, Joan was something of a catch.

A tall, slender brunette, she was said to have turned down an American millionaire to become Countess of Cardigan. A year after that wedding, a more conventional ceremony followed at St Mark’s church, Mayfair.

According to a family historian who interviewed Ailesbury, his mother was neglected by his father after the birth of her two sons. ‘This may explain why he never adopted the Cardigan title,’ says the historian.

As for his own marital history, the marquess did not tie the knot for a fourth time.

For her part, Teresa, the woman who was so devoted to the marquess, says: ‘We didn’t marry because we were very happy the way we were. Everyone thought I was the marchioness anyway, so why bother? Michael was my darling, we had a wonderful life together.’

That all ended one evening a few weeks ago, when she found her partner face down on the terrace of their home. ‘I had last seen him reading a copy of the Spectator magazine in a chair in the garden,’ she said.

One theory is that he had gone to his bedroom - where a cushion on the bed carries the slogan ‘older men make better lovers’ - to rescue the family cat. His slippers were against the wall and the sash window, which was open, had no restraining bar.

In a clan where drama has been so much a part of the fabric of family life, it is unlikely we have heard the last of the affair.