By Lauren Fletcher & Joseph Wilkes Royal Family watchers have rushed to point out an embarrassing error in Sarah Ferguson’s sentimental birthday tribute to the late Queen Elizabeth II posted on Instagram. Known to have been close to Her Majesty, the Duchess of York marked what would have been the Queen’s “97th” birthday by sharing an endearing snapshot of the late Queen with an affectionate note. Sarah penned: “Today we are remembering Her Late Majesty Queen Elizabeth II on what would have been her 97th birthday. Thank you for all that you have taught us, for being a steadfast leader and dear …