Can anyone ID this caterpillar?

Hi there,

Can anyone help identify this caterpillar that arrived home with my lettuce from the supermarket. Thankfully I'd removed a few layers of it and found this guy working its way through some of the leaves. I've been feeding it on bits of the lettuce over the past 2 weeks and it has grown substantially; it was probably half its size both length and width when I first found it. However, I've no idea what type of caterpillar it is! The county of origin on the label of the lettuce says Spain, though I've found nothing online that really resembles it. It's just over an inch long at this point.

Anyone here have any idea? Link below