LONDON (Reuters) – Britain’s royals will gather at London’s Westminster Abbey on Friday for what has become an annual Christmas carol concert hosted by Kate, the Princess of Wales. Kate will be joined by her husband Prince William, the heir to the throne, who will give a reading during the service at the Abbey where King Charles was crowned in May and the funeral for Queen Elizabeth was held last year. Guests will include those from charities connected to the royals, and the event will feature musical performances from singer-songwriter Freya Ridings and a duet from soul artist Beverley Knight…