Complex sentence: Years ago, Umezaki's father abandoned him and his mother while away in England, and in a letter his father wrote that he was so impressed by the brilliant Holmes that he resolved to stay in England forever.
Split into simpler sentences: Years ago, Umezaki's father abandoned him and his mother while away in England. In a letter, his father wrote that he was so impressed by the brilliant Sherlock Holmes that he resolved to stay in England forever.