The long aristocratic line of the Lytton family, owners of Knebworth House, is full of colour, but it has also held a dark secret – one that has not been fully told until now.

The Comet: Edward Bulwer-Lytton. Picture: Courtesy of Henry Lytton CobboldEdward Bulwer-Lytton. Picture: Courtesy of Henry Lytton Cobbold (Image: Archant)

In April 1848, the 19-year-old daughter of Edward Bulwer-Lytton – a renowned author whose popularity once rivalled that of Charles Dickens – died in a cheap London boarding house, apparently abandoned.

In a new book released this week, Bulwer-Lytton’s descendant Henry Lytton Cobbold literally breaks into the mausoleum of the stately home to uncover the life and death of his ancestor’s first-born child, Emily Bulwer-Lytton.

Emily, Henry said, was driven to suicide by issues including her parents’ scandal-ridden marriage, her father’s womanising, and embarrassment over her own affairs – one of which was with a 15-year-old boy.

Research for the prodigious two-volume work, a collaboration with Mary Letitia Greene, took Henry on what he calls a ‘17-year odyssey’ of investigation.

The Comet: Henry Lytton Cobbold at the Knebworth House mausoleum. Picture: Courtesy of Henry Lytton CobboldHenry Lytton Cobbold at the Knebworth House mausoleum. Picture: Courtesy of Henry Lytton Cobbold (Image: Archant)

Henry, 54, told the Comet: “It’s an extraordinary story, and that’s why it’s taken so long. It all started in 1999, when we broke into the mausoleum with a hammer. My grandmother had bricked it up in the ’50s because of thieves, but before she died she wanted to do some work on it.”

Inside, one of the seven coffins had been wrenched open, with the skeleton of a slight young woman inside.

“To be confronted by her open coffin – I didn’t feel at the time that I wanted to look,” said Henry.

After the builder accompanying him had a look at the skeleton, Henry established that this was Emily, his great-great-great-aunt, who had suffered from curvature of the spine and also been diagnosed with polio.

The Comet: Emily Bulwer-Lytton's coffin in the Knebworth House mausoleum. Picture: Courtesy of Henry Lytton CobboldEmily Bulwer-Lytton's coffin in the Knebworth House mausoleum. Picture: Courtesy of Henry Lytton Cobbold (Image: Archant)

Her cause of death was given as typhus, which briefly caused Henry and the builder some concern as to their own health.

But Henry now thinks that Emily killed herself by overdosing on the laudanum she had been given for toothache. Suicide then being illegal, the family would have worked to cover this up.

Henry said: “I knew the legend of this girl, which had been passed down to me, but she’s the only member of my family who’d never been written about. I never really believed she died from typhus.

“This set me off on this 17-year odyssey, and I now have found the truth.”

The Comet: Part of a letter written by Emily Bulwer-Lytton. Letters were often then 'cross-written' to save on postage, with the writer turning the page 90 degrees and continuing to write on top of the previous lines. Picture: Courtesy of Henry Lytton CobboldPart of a letter written by Emily Bulwer-Lytton. Letters were often then 'cross-written' to save on postage, with the writer turning the page 90 degrees and continuing to write on top of the previous lines. Picture: Courtesy of Henry Lytton Cobbold (Image: Archant)

The years of research took Henry across the continent, and involved reading through and transcribing reams of letters – a difficult task, as they were ‘cross-written’ in typical 1840s style.

Henry explained: “To save on postage, they would write on a page and then turn it 90 degrees and write over the top again – so reading them becomes a labyrinthian undertaking.

“They’re all transcribed now and they throw more truth on the legend. It’s not really true she had a miserable life. There was plenty of joy there.”

He added: “Her parents’ marriage was a disaster, and was the cause for a lot of her problems. But the big mystery about her death is confirmed.

The Comet: Henry Lytton Cobbold signs copies of the book. Picture: Courtesy of Henry Lytton CobboldHenry Lytton Cobbold signs copies of the book. Picture: Courtesy of Henry Lytton Cobbold (Image: Archant)

“It’s a real Agatha Christie mystery and we’ll never be able to prove the true reason, but having done the work and really looked into it I’m convinced it was suicide by any other name.

“Whether she quaffed a whole bottle of laudanum by herself or something else, certainly she thought she had no reason to live. It was a very sad teenage suicide.”

He added: “Last June, having finished the book, we went back with flowers from the Knebworth House garden and from Germany, where she played as a child. For the first time I did look, and come face to face with her – and we finally sealed the coffin for good. It was a very moving moment.”

The two-volume work, spanning 992 pages in total, includes previously unpublished letters and photographs in full colour.

The Comet: Flowers on Emily Bulwer-Lytton's coffin in July 2016. Picture: Courtesy of Henry Lytton CobboldFlowers on Emily Bulwer-Lytton's coffin in July 2016. Picture: Courtesy of Henry Lytton Cobbold (Image: Archant)

In the Bosom of Her Father: The Life and Death of Emily Bulwer-Lytton is published in two volumes by 39 Production – price £80.