Hibernia

[marka]

most of the western provinces didn't pay for themselves at least britain had good farm lands and resources ie tin.There were probably more strategic reasons for holding gaul and britain ie population movement control

Ireland had timber, wolfhounds gold and the most talented goldsmiths in western europe 8)

wherabouts where the gold deposits?where there any tin mines?
add slaves as well of course.
if the gold deposits were large i'm surprised the roman didn't try at least one invasion (gold was certainly one reason for invading dacia)