Kate Middleton London - Arabstoday   Rumour has it that US Vogue editor Anna Wintour and royal photographer Mario Testino are to team up with the Duchess of Cambridge for a forthcoming Vogue covershoot. The rumour mill is churning that the Duchess of Cambridge is finally going to cement her style credentials by posing for the cover of fashion bible, US Vogue. It is thought that Anna Wintour, the British editor-in-chief of the magazine, has been encouraging noted photographer Mario Testino to ask Kate to take part in the photoshoot. Wintour has been quoted as saying \"There\'s nothing trashy or vulgar about her [Kate]…she dresses her age and never looks out of place.\" Mario Testino has been a close family friend to the royals for many years. He photographed Princess Diana on a number of landmark occasions, earning him the label of \'Diana\'s favourite photographer\'. Diana commissioned Testino to shoot her with her two young sons for Christmas portraits in 1994, and the Peruvian photographer was famously the last person to take her picture, for Vanity Fair magazine in July 1997, before her death. After Diana\'s death his relationship with the princes continued, with Testino most recently asked to take Prince William and Kate Middleton\'s official engagement portraits in December 2010 - although he was not the couple\'s wedding photographer. A source told American newspaper The New York Post that \"Anna [Wintour] has been speaking to Mario about winning over Kate. She is really pressing him to shoot Kate for the cover\" while another said that \"every magazine has been trying to get Kate, and many assume it will eventually be Vogue. But even with the Mario Testino relationship, it is not clear when this will happen. The Palace must approve it, and they are very protective of Kate.\" Before her wedding Kate was offered the chance to appear of the cover of British Vogue by editor Alexandra Shulman, but the declined the invitation. It is believed that the royal family are not totally adverse to the idea of appearing of the cover of Vogue, given the fact that Princess Diana sat for the publication three times. Both Kate and her sister Pippa have previously appeared on the cover of British society magazine Tatler, although both images were reworked archive photos. And while the Duchess\' engagement photographs were featured on the cover of the July issue of Vanity Fair, she has never officially sat for a magazine covershoot. No doubt British Vogue will be hoping to be top of Kate\'s list whould she decide to follow in the footsteps of her late mother-in-law. Representatives for US Vogue, Mario Testino and Buckingham Palace declined to comment last night. From, Vogue.co.uk.