Expert Help needed please?

I have a very small photograph which I know is my granddad (the only photo I have of him). He is standing on the railway box and I could never imagine that it would be possible to able to see what he looked like. However, a cousin has now told me that she has the same photo and her husband has expanded the photo up to around and between A3 - A4 and that it is amazingly clear and you can see his face ok. She has tried to e-mail it to me without success, so I wondered why I couldn't do the same with mine. I am not very experienced at doing things like that, but I started by scanning it at 600dpi (as I have seen that is what is recommended on here). I also played a little with some settings. The two photos (below) do seem to be better than when I scanned it on 300dpi, but when I tried cropping them (see below) it still isn't clear enough.

Can anyone suggest please what, if anything, I can do to improve it enough to see his face more clearly? Or what her husband must have done to get it so good?

Expert Help needed please?