Known prominently for his role as Number 6 in The Prisoner, he was in a number of films as well. Click here to read the AP article about his death.
Dan has a lengthy review of the series here, where he also notes:
"It was a very expensive show to produce during its day, & ultimately was considered a financial failure. The furor over fan reaction to the series’ final episode caused PM to leave the U.K, & actively seek stage & film work stateside. The show’s brevity is 1 of the factors in its becoming a cult favorite... But, truly, the real reason is that great art usually is not appreciated at 1st blush- it takes time for the masses to digest & appreciate."