The example, below, is the handwriting of Anne Boleyn in 1514. I consider it to be the most valid physical evidence available to argue that Anne Boleyn was older than some scholars claim.

Most of Anne's biographies lean toward a birth year of either 1501 or 1507. Some speculate that she might have been born as early as 1499.

If Anne had been born in 1507, she would have been seven years old at the time she wrote this letter (See Anne Boleyn's Birth Year). She did not have the advantage of lined notebook paper, yet her handwriting is small and consistent, and her lines are remarkably evenly spaced. This is not an ability enjoyed by most, if any, seven year olds.

See if you agree:

This sample (in French, her SECOND language) contains sentences that are lengthy and complex, words that are long, and handwriting that is confident and smooth. If she were copying the longer words, the handwriting would show hesitancy. Instead, the errors she makes (see where she corrects words above the line - these corrections are not at all clumsy) appear to be from speed or afterthought rather than inexperience in writing. 

While some people argue that children in the 1500s received more training than modern children, and therefore could achieve more advanced results at an earlier age, studies of modern parents who aggressively train their children, even from infancy (including some who begin audio stimulation in the womb), reveal that such children do not demonstrate advanced capabilities by the third grade.

Below is an example of the handwriting of a seven-year-old child in English, his FIRST language. Compare the sentence structure (you can ascertain, without knowing French, that the flow of thought in Anne's letter is more mature just by sentence length alone), the word choices, the inconsistent sizing and spacing, and manner in which he forms each letter:

My conclusion based on this comparison is that Anne Boleyn was an adolescent at the time she wrote that letter in 1514, and therefore was born between 1499 and 1502.

Anne Boleyn's handwriting example was scanned from "The Rise and Fall of Anne Boleyn" by Retha Warnicke.