I may be wrong but I think the source of his grievance is not racial hatred, but a real snobbishness at heart, and an annoyance that someone who, by Clarkson's lights, is a hick from the sticks, could be the PM of what he probably always refers to as "England" although cartographers and historians know it as the United Kingdom.
I think the reality of the United Kingdom is acknowledged by a slightly wider circle of people than just "cartographers and historians", but that's by the by. I can definitely see her point here, but her argument from this point forward goes a bit haywire:
But nor do I classify the mirror image of Jeremy Clarkson's boorishness towards Gordon Brown as racism as it was experienced by brown, coffee-coloured and black-skinned people in South Africa, Jews in Hitler's Europe, the Chechens and African Americans. This list, which is by no means comprehensive, is of people who have learned the difference between racism and national resentment through cruelty, torture and the structural discrimination against them in their countries' laws.
If you make a person's race (or nation) a criterion upon which you judge their worth, then you are guilty of racism.
If you throw an "English","Irish", "Scottish", "Welsh" or even a "British" into an insult to make it more hurtful or to increase its (in your own mind) effectiveness- then, by extension, you're guilty of more than just mere "mean-spirted nationalism".