Mail Signature is erratic

When replying or forwarding a message using Mail, I often want to add my signature.

However whereas in an original mail the signature is always placed at the end of the mail, when forwarding or replying it is often places randomly in the middle of the mail (useless/stupid).

I thought at first that it was because my cursor was not at the end of my message, but not at all; wherever I leave the cursor the signature always returns to the random point (often after a return paragraph).

This is very annoying as the only work around is to the select, cut and paste the signature in the right place.

I thought that an up-date would have sorted the problem, but this has existed for over a year now.