The invitation in question was for the traditional Christmas lunch at Sandringham, and it marked a significant departure from tradition as Kate was still considered an "unregistered girlfriend."According to insights from royal expert Robert Lacey, Kate had her own perspective on this matter.
She made it clear that she would only join the Sandringham Christmas Day festivities when she and William were engaged, and she had a ring to signify their commitment. This demand for a proposal seemed to reflect her determination to take their relationship to the next level.
At that point in their journey, the couple was facing some challenges in their relationship. William was grappling with second thoughts about their future together, prompting him to engage in frank discussions with both his father and his grandmother regarding his relationship with Kate.
This refusal to attend the royal Christmas event marked a pivotal moment in their courtship, highlighting the complexities of their romance.