Alf, I don't recommend shoe polish on vintage leather. It is a mixture of pigments, water repellants, oils and other things you should not use on Luger holsters.
What you need is dye.
please research this project before you put anything on it.
I and some others have written thousands of words here , search the site for advice.
http://cgi.ebay.com/ebaymotors/CONNO...spagenameZWDVW
Jerry Burney