Randolph Wright

 was Polly's patrilineal uncle. He died in a Nazi prisoner of war camp during World War II. He was survived by his older brother, Polly's father, who honoured his younger brother's memory by telling young Polly tales of her uncle after the war. (CC: Resistance)
 * That Randolph's surname is mentioned in Resistance is significant. Polly's surname, by contrast, was never mentioned in any bit of performed Doctor Who up to this point. "Wright" had instead derived from the Gary Russell book, Invasion of the Cat-People.  The explicit mention of his last name in a piece of performed Doctor Who'' thus gives the name "Polly Wright" a measure of wider acceptance and therefore greater authority.