I've tried things like noise and sepia, neither of which I find very convincing. Looking through a huge box of family photos my mum had, going back to the 1940s, I honestly can't remember a single one having a noticeable sepia tint. I think sepia is something people expect to see in an old photo merely because it's old, not because its actually there. Personal opinion and personal optician's prescription, of course.

Here's the result of using a warming filter in Elements, on the picture above. It's not really sepia, so much as slightly faded black and white...something like that. This would have been taken in the early 1960s, so which of the two pictures below do you find the more convincing - the original one, as previously posted:


...or this one with the warming filter applied:

EDIT: Actually, now I can see them both together, I think the second one is more convincing.
EDIT: Inserted the final one between the two above