I have a folder of stamps, most of them came from my grandfather, they are the leftovers after he sold off the bulk of his collection. They are loose, i.e. not hinged to the folder but behind clear plastic 'shelves' if that makes any sense. I bought the folder I keep them in when I was a teenager. There are a few thousand, I would guess about 4-5000? They are pretty much all pre-1970, some much older, right back to Queen Victoria 1d. reds. Countries are worldwide with quite a preponderance of GB, USA, Canada and Australia as you might expect to find in this country (letters from emigrant relatives I suppose). They are mostly franked.
I can photograph or scan and list them without too much trouble, the thing I'm not sure about is how to value them? Stanley Gibbons stamp catalogues from the library I suppose? Would I be better off to list them in groups or as singles? Any other suggestions for how to value them?
Any ideas welcome, I am a bit out of my depth as I haven't had anything to do with stamps since I was a teenager. Thanks!