Recently my mother brought out a box of my grandfather's papers that she'd never gone through before. My grandfather died in the 1990s when he was in his late 80s, and he was a fairly prominent British doctor in his day. In the box is an envelope marked 'photographs given to me by the wartime heroine lady doctor who ran a hidden hospital in the woods in yugoslavia and walked the children over the mountains to safety at the end of the war.' The envelope holds around fifty or so wartime photographs. Two or three are fairly graphic war shots, others are more everyday snapshots of children in the woods or walking on a long trek. I assume that my grandfather was only given copies of these photographs but I would hate it if I was hoarding the only copy of images that might be very meaningful to someone. I've done a reverse search on two of the photographs and nothing came up but my technical skills aren't great so I might have been doing this wrong. Could any kind historian advise me on the best way to proceed? Thank you.
Hospital archivist here! One thing you could consider is offering to donate the photographs to the archives at an institution your grandfather was associated with - think his medical school, a hospital he worked at for many years. If he was quite noted in his field, there's a good chance someone will want his papers. For a lot of archives, that connection to the institution is just as important if not more than the subject. If you do this, try not to disturb the photos too much if you haven't already - leave them as they were found, and make sure to preserve any notes and things you found with his papers. That all adds context that will potentially make the collection more valuable for research.
I don't know if the mods will allow this comment, but please feel free to DM me if you'd like! I'm an archivist in the US, but I'd be happy to help where I can.
For storage: photos should be kept cool and dry, away from acidic paper, stored in a dry box. If you or your mom know any of the people in the photos, make a note in pencil on the backs. Putting names to family members and family friends will be something easier for you to do than any future researcher.
You could try the Imperial War Museum (I’m presuming from your post that you are in the UK). Their website is here https://www.iwm.org.uk/collections/managing/offer-material. Unfortunately they are closed at the moment due to COVID19 but they will probably get up and running again. They are one of the main resources for military historians so there would be a decent chance of someone using it.