Victoria Beckham says her 50th birthday pictures prove she’s not a “miserable cow”. The former Spice Girls singer threw a party at the end of April to mark hitting the milestone age, and was seen smiling in pictures posted online by pals – and in images captured by photographers who snapped her being piggybacked by her husband David Beckham, 49, out of the Mayfair private members’ club that hosted the bash. She told Grazia about how the images are an accurate portrayal of her personality: “They showed the world who I really was. That is the real me. So it’s like, ‘Happy birthday, all that hard…