MPs retirement age

Why are MPs allowed to keep working way beyond the retirement age for all other individuals? Apparently it's because their allowances and salaries are so good. If they expect everyone else to retire at 65, and 60 for most civil servants. Then they should also be expected to retire at 65 if not 60. Ironically , if this rule had been in place in the past, Winston Churchill would never have had his "Finest Hour" as he was over 65 when he became Prime Minister in 1940.