This was on the RSPB website under Population Trends:
"In the UK the population decline began in the 18th century as a result of severe persecution by sheep farmers, which was aggravated in the 19th century by shooting by gamekeepers. A further major decline came in 1950s and 1960s when pesticides concentrated in the bodies of eagles causing widespread infertility and eggshell thinning. The golden eagle was exterminated in England and Wales by 1850, and in Ireland by 1912. Despite severe persecution, it managed to survive in small numbers in Scotland."
I imagine the last ones were in the Lakes and/or Snowdonia.
Cheers
Ray