At his death, Wren was also survived by his son Percival Rupert Christopher Wren, born in Karachi in 1904. Percival Wren reportedly did not have a close relationship with his father, and the two ceased to have any contact after the son went to live in the United States during the 1920s. Wren also adopted Isabel's son from her first marriage, Richard Alan Graham-Smith, as his own. After many years in a successful teaching career, Graham-Smith, known to most people simply as Alan, retired to Devon, where he lived in the South Hams coastal village of Torcross until his death on 31 December 2006 at the age of 96. Graham-Smith ended up becoming the sole administrator of Wren's estate for many years and possibly the last living person to have any personal acquaintance with Wren. He strongly maintained that Wren had indeed served in the French Foreign Legion, and was always quick to contradict those who said otherwise.