I bet that Romney aide was trying to talk about "Anglo-American heritage", because that's a real thing that people say, and it goes along with the term "special relationship between England and the United States."
And it just came out as "Anglo-Saxon heritage", because the aide had one of those brain-frotzes where your brain takes the beginning of a term, and autofills the rest of the term without consulting you, and "Anglo-Saxon" is the term that comes in before (heck, on Google, it's 27 million hits for "Anglo-American" and 50.5 million for "Anglo-Saxon", so I bet the aide's brain just autofilled it wrong.)
And it just came out as "Anglo-Saxon heritage", because the aide had one of those brain-frotzes where your brain takes the beginning of a term, and autofills the rest of the term without consulting you, and "Anglo-Saxon" is the term that comes in before (heck, on Google, it's 27 million hits for "Anglo-American" and 50.5 million for "Anglo-Saxon", so I bet the aide's brain just autofilled it wrong.)