Another native English person here, so usual disclaimers. I have visited and traveled extensively from an early age around the southern Netherlands (Noord-Brabant) due to my parents meeting and befriending a Dutch couple whilst traveling there before I was born.

I have found levels of English there to also be excellent, one possible reason could be that English language television and radio broadcasts (BBC etc) have been available to the Dutch for decades, and in a lot of cases actively consumed. That was certainly the case when I was there as a child.