(FILE PHOTO) In this photo composite image a comparison has been made between, Left; KLOSTERS, SWITZERLAND - FEBRUARY 06: Princess Diana On A Ski-ing Holiday. The Princess Is Wearing A Red 'head' Ski Suit And A Headband And She Is Holding A Pair Of 'dynamic' Skis. (Photo by Tim Graham Photo Library via Getty Images) and Right; KLOSTERS, SWITZERLAND - MARCH 30: Kate Middleton, girlfriend of Prince William join in with the royal ski party in Klosters on March 30, 2005 in Switzerland. (Photo by Tim Graham Photo Library via Getty Images). Kate Middleton will be celebrating her 26th Birthday on January 9, 2008.