This is the Community of users for the Photos app, and you haven't mentioned that, so that's why I'm confused, as well.
Is Tim 1 the filename, like "Tim 1.jpg?" Or is it a title in Photos?
As I said earlier, if your pictures are in a Finder folder, you can choose View>Sort, like this:

"Sort by None," meaning you move them to the order you want, is not available in List view.
In Photos, I usually sort by Title:

In a Photos Album (but not in other views) you can move the pictures to a custom order, and then none of the choices above will have a check.
The external drive does not manipulate your pictures; apps do. You haven't said what app you're using. Again, are you using Photos or Finder or some other app?
If you don't know, then you could include a screenshot to help Old Toad and me to figure out what you mean.