Photographs can be deceptive but looking at the leather I feel that it started out from the Tannery as Aniline Leather rather than the coated variety. Because it looks like the adhesive tape has removed some of the leather top coat that has been applied over the years to keep the leather in good condition hence the fine leather patina you have on the case.
The one place that requires some attention is the case hinge line it is cracked the reason is not as a lot of people think the constant opening and closing but moisture leaving the leather causing it to harden and then eventually cracking due to the movement.
Aniline Leather is tanned using vegetable tanning usually Oak bark and dyed with vegetable dyes and having no to surface coating. But the one important thing it undergoes is treating with oil to seal in the residual moisture to keep it supple but over time moisture and oil is lost. In times past the Oil used on the hides was a mixture of “Neatsfoot Oil” and Fish oil usually “Cod Liver Oil” the ideal would be to use all Neatsfoot Oil fish oil was added to reduce the cost.
So treat the hinge line with Neatsfoot oil clean the case with saddle soap then finish with saddle polish all items can be obtained at a Equestrian Tack suppliers (sorry I don’t know the name for them on your side of the pond) take your time and don’t over clean it.
