Jamie Redknapp marked his youngest son Beau's 13th birthday in the sweetest way on Wednesday.MORE: Jamie Redknapp and new wife Frida Andersson look smitten the morning after surprise weddingTaking to Instagram, the former professional footballer - who recently surprised fans with news of his secret wedding to Frida Andersson - shared a series of adorable throwbacks of his "little man" as he paid a heartwarming tribute.WATCH: Louise Redknapp shares rare video of son - and it has fans in