By Michael Holden LONDON (Reuters) – The last year will go down as one of the most seismic in the history of the British royal family with the death of Queen Elizabeth months after she celebrated her record seventh decade as monarch, but 2023 could prove almost as momentous. In February, Elizabeth, who broke pretty much every record for a monarch in a dynasty stretching back 1,000 years to the Norman invasion of England, marked 70 years on the throne, with four days of national celebrations following in early summer. But there were already signs the 96-year-old’s health was failing. Her public…