"At first blush, Thomas and his friends seem rather placid and mild. And there are certainly a lot worse shows in terms of in-your-face violence, sexism, racism and classism. But looks can be deceiving: the constant bent of messages about friendship, work, class, gender and race sends my kid the absolute wrong message."
And don't think Britain's imperial history is not worthy of mention: the writer, Tracy Van Slyke ("a fellow at the The Opportunity Agenda, where she researches and writes about the intersection of social justice and pop culture"), also describes the Isle of Sodor as seeming "to be forever caught in British colonial times", a phrase which is hard to make sense of (is she suggesting that Sodor is a colony? is she aware that the books were in fact written at a time when Britain had a few more colonies than it has nowadays?).
I'm with Ms Van Slyke in disliking the cartoons. But the Guardian might find more to like in the source material: Wikipedia tells me that Mr Awdry taught in a school in Jerusalem for 3 years, educating Palestinian Muslims (if Wikipedia's entry on the school in question is to be believed) and was a pacifist during WWII.