He was a valet, she was a kitchen maid and more than a century ago they met because of his passion for photography and desperate need of a warm place to use as a makeshift studio.

Alf Edwards and Caroline Palmer worked at opposite ends of an imposing country house, set in a huge estate with hundreds of employees, and there was little other reason for their paths to cross.

But they did and they fell in love and married despite everyone advising them not to.

The poignant, Edwardian below-stairs love story of Alf and Caroline is revealed in what English Heritage says is the most significant and biggest donation of objects relating to servants that it has ever received.

The couple’s grandson Gordon Edwards donated more than 60 objects, which include photographs, letters, postcards and personal items such as Alf’s camera, Caroline’s gold watch and a handmade engagement present.

They document a story that could be a plot line from Downton Abbey, and add more widely to understanding of life at Brodsworth Hall, near Doncaster, a Victorian country house once owned by the “shoot-in-winter, yacht-in-summer” Thellusson family.

“It is a fabulous story and a fabulous group of objects,” said Eleanor Matthews, English Heritage’s curator of collections and interiors. “Collections like this just don’t survive.”

Matthews said Brodsworth had always been very good at telling the stories of people who worked at the house. “But having objects that the servants owned, used, looked at, had in their rooms whilst they were working at the house … that just makes it super-special.”

Alf and Caroline were the employees of Charles and Constance Thellusson, whose ancestor Peter Thellusson had bought the Brodsworth estate in 1791.

Peter Thellusson had amassed a huge fortune, a substantial part of it linked to the transatlantic slave economy. When he died he left what has been described as “one of the most spectacularly vindictive wills in British history”, with the bulk of it left in trust for as yet unborn descendants.

The current Brodsworth Hall was built between 1861-63 and survives, virtually unchanged, as a mid-Victorian vision of a comfortable country house.

It was here, as the first world war loomed, that Alf and Caroline met because of his enthusiasm for photography.

They began courting and were quickly engaged, perhaps because of the times. Many men employed at Brodsworth were conscripted but Alf, because of ill-health, was unable to sign up.

Soon Caroline was promoted to cook at Brodsworth and Alf took on extra duties including becoming chauffeur.

His poor health led everyone to advise the couple not to marry and they briefly separated. But the parting was too much and on 17 July 1916 they married and had three happy years, during which time Caroline gave birth to two boys, before Alf died from tuberculosis aged 34.

Matthews said Caroline lived a long life and always talked fondly of her time at Brodsworth.

The donated objects include Alf’s camera, made by Eastman Kodak of Rochester New York and possibly purchased on a trip he took to the east coast of the US with the Thellussons in 1914.

There is also what is thought to be Alf’s engagement present to Caroline – a wooden picture frame handcarved by him with a good luck message and a horse shoe fixed to it.

A number of the objects have now gone on display at the house and the hope is they may help to unlock other stories.

Matthews said the trove included the earliest image of staff at the estate. “Hopefully in time we will be able to identify them all,” she said.

“These beautiful, poignant items tell a story largely unknown to us until now and, thanks to the donation, we are able to add another layer of understanding to the rich fabric of Brodsworth’s history.”

While the collection is catalogued and conserved, a few select pieces including Alf’s camera, the carved wooden stool, three pipes, first world war registration cards, postcards, and Caroline’s wedding wristwatch will go on display for the first time at Brodsworth Hall from Wednesday.