Prince Harry and Meghan Markle have declined an invitation to spend Christmas at Althorp, the ancestral home of Princess Diana’s family, due to ongoing security concerns for their children, according to inside sources. The Duke and Duchess of Sussex are reluctant to bring their children into what they perceive as a potentially dangerous situation in the UK, which Prince Harry previously confirmed in an interview. He told ITV earlier this year: “All it takes is one lone actor, one person who reads this stuff to act on what they have read. “And whether it’s a knife or acid, whatever it is, these…