Good for McDiarmid, the perfect actor for the role.
McDiarmid was surprised when Lucas approached him 16 years
after Return of the Jedi to reprise the role of Palpatine. In an
interview, he stated, "When we were doing Return of the Jedi there
was a rumor that George Lucas had nine films in his head, and he'd
clearly just completed three of them." McDiarmid added, "Someone
said that, 'Oh, I think what he might do next is go back in time,
and show how Vader came to be.' It never occurred to me in a
million years that I would be involved in that, because I thought,
'oh well, then he'll get a much younger actor [to play Palpatine].'
That would be obvious." However, "I was the right age, ironically,
for the first prequel when it was made. ... So I was in the very
strange and rather wonderful paradox of playing myself when young
at my own age, having played myself previously when
100-and-I-don't-know-what."
https://en.wikipedia.org/wiki/Palpatine#Portrayal
