Who are the forgotten First World War nurses?
It is an international search. After Auberon Herbert, the 9th Baron Lucas and owner of Wrest park in Bedfordshire offered his stately home to the government for use as a place to treat wounded servicemen, it took just a week to transform it into a hospital.
His sister helped find nurses - some came from Australia and New Zealand - but many were simply volunteers, with no medical training, middle class women who wanted to do their but to help the war effort.
More than 100 answered the call, but the haste of the operation meant there were few formal records of the nurses to start with and what remained was destroyed in a fire in 1916.
But there were some original photographs. And by transforming them into colour pictures, thanks to the expert colourist Marina Amaral, it's hoped the images have become almost more real - real enough for someone to identify the women, to be able to tell their stories, where they were from, their full names and ages, their family histories.
And because some of the women were from abroad, the hunt for information will go beyond the UK.
The women who cleaned the wards and made the beds, changed wound dressings and helped at the surgeries were vital to the running of the hospital, from the moment the wounded soldiers were transported to the building, having survived the horrors of the Western Front but with sometimes terrible injuries.
The atmosphere wasn't always sombre. One of the images shows a nurse, Nurse Cockburn standing by a soldier who is also dressed in a nurse's uniform, and there were parties and theatre shows at the house too.
There was a dispensary set up in the vestibule on the ground floor of the mansion - Sister Warner can be seen concentrating as she takes medicines off the shelves.
They are delightful pictures. And English Heritage is urging anyone who recognises any of the faces to contact Wrest Park's Volunteer History Team on: wresthistoryvolunteers@english-heritage.org.uk