Eton College is poised to reveal its next head master in the coming weeks, with Alastair Chirnside emerging as the leading contender for one of British education's most prestigious positions.It was announced earlier this week that Prince George, 12, will attend Eton, the same institution as his father, Prince William, and uncle, Prince Harry, ending months of speculation.Mr Chirnside, who currently serves as warden at St Edward's School in Oxfor…