In Scandinavian we say "førrn i tiden" to express "In the old days we had horses and farm." It is a descriptive form.
To translate "I gamle dage" correct I would say "In the past the king had his servants who tasted the kings food to make sure it wasn't poisoned." It is a past tense in a more concrete form. A more old fashioned expression
"I gamle dage" you also lack the important final-r "I gamle dager", if that -r would have been present then it would have been much more descriptive, and more alike the first variety.
It might seem like small variations but that is the difference between a w-b-w translation and a translation.
Hope you feel a little more understanding!
/Porfyhr