I may be wrong but I think you ll be hard pressed to find significant coverage in reliable sources that the 1000th person on the old list is the 1000th person in line for the British Throne or indeed that they have any connection to the British Royal family If I look at the nearest one to the 100th Count Folke Bernadotte 1896 1948 the first extent biography has no mention of him being part of the British Royal Family at all and neither does his wp article either