Box Sets of the Thomas Series???

DVDs were region locked because of how films were released in the past, where some places got films out in DVD up to 6 months before another region. (The only example I can think of is Finding Nemo) They were locked to prevent people simply importing a foreign copy of the film to watch it sometimes before it even came to cinemas in the region. The loophole was that you could simply import a DVD player from the region as well and get around the lock. After DVD player regions were unlocked, however, this is no longer necessary.