Complex sentence: In 1890, the countess became a Lady of the Bedchamber to Queen Victoria until the latter's death in 1901 and was continued as such under Queen Alexandra until Edward VII's death in 1910.
Split into simpler sentences: In 1890, the countess became a Lady of the Bedchamber to Queen Victoria until the latter's death in 1901. She was reappointed as such under Queen Alexandra in 1901 and until Edward VII's death in 1910.