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 brother, Polly's father, who honoured his 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 Target Books range of novelisations.  The explicit mention of his last name thus gives the name "Polly Wright" a measure of greater authority.