Hi,
I too agree that Reference letter issued by previous employer (years before) is sufficient as proof of employment. I worked for 12 plus years with my previous employer and resigned during 2008. I submitted reference letters issued be 2 senior executives, appointment letter, promotion letter, appreciation letters, salary slips, IT Returns, Service Letter etc etc as proof of my job. If I need a current dated reference letter from my previous employer it is not at all possible.
So in my opinion, there is no need for a current dated reference letter for previous employment if any.
Satish