Susjwp from your post I take it that you would like to get from this poor specimen of a case
Well it is not difficult to do but it does take some time.
first thing to do is remove wax and polish with a solvent this will also clean the leather somewhat. I do know I will get a lot of complaints but I do prefer to use Petrol outside in the fresh air, other solvents are available.
All old leather restoration should start with a good clean, using warm water with a drop or two detergent and a fine spray bottle just dampen the leather surface then with a cloth rub the moisture into the leather this will also remove dirt that the solvent did not this will also open the pores to allow other treatments to enter the leather. The water is most important because it is moisture that the leather looses making it hard and brittle. Now to feed the leather you can purchase all sorts of potions from not a lot of cash to a stupid amount, I use only two one makes the lady I live with angry not to put too finer point on it though she does calm down when she gets a new replacement. I usually borrow a pot of her expensive moisturizer well leather is only skin after all though I do not know if E45 cream is available on your side of the pond that works just as well as the best leather conditioners though the wife's cream does take the musty smell off the leather replacing with something more pleasant. For very old dry and hard leather I have found nothing better than 50 50 Cod Liver Oil and Neatsfoot Oil though you must rub it in to the leather sparingly. Now I colour the leather food and the oil mix with leather dye to help bring back the leathers colour. at this point I do find that the nearsfoot oil mix works miracles on the case hinge leather stopping the usual cracking from getting any worse. As for cuts and gouges you can purchase leather fillers there being many varieties some co loured and others just white they work well hiding a lot of ware and tear marks. If you apply the moisturizer say every other day the leather will respond well for my final finish I like to use color shoe restoration polish applied with a cloth then left for twenty four hours then buffed up with a soft brush.
Ho[e this is of some help.