The old joke is you find gentlemen trying to be auctioneers at Christie’s; at Sotheby’s it’s the other way round. So you may be surprised Sotheby’s, 1744, is the senior; Christie’s is an upstart founded in 1766.
A 20th century author (1897 – 1976) who wrote more than forty books, lots adapted for film, TV and the wireless, had four wives, two children and he has never been mentioned in almost 2,600 posts – incroyable!