[of the time] or [at the time]

[ansonman]

I have made up the sentences below.

(1a) When I was young, I worked at a government agency. Some of the politicians at the time were very famous.

(1a) When I was young, I worked at a government agency. Some of the politicians of the time were very famous.

Which preposition for "time" is correct? Thank you for your help.

[Alan]

at