Dame Diana Rigg plays the Duchess of Buccleuch a new lady-in-waiting in season 2, However the real Duchess of Buccleuch was only 30 when she became the queens lady-in-waiting.
The writing method of the 19th century and well into the 20th century relied on children being first taught to hold then pens and pencils correctly and then being taught to write. Queen Victoria's method of holding her pen is clear in many of the images of her writing at her desk. Jenna Coleman in S2 E1 clearly is seen holding her pen in the modern "untaught" monkey grips style.