Was heißt »seinerzeit« auf Englisch?

Das Adverb »seinerzeit« lässt sich wie folgt von Deutsch auf Englisch übersetzen:

Deutsch/Englische Beispielübersetzungen

Philidor galt seinerzeit als der beste Schachspieler der Welt. Nach ihm benannt ist die Philidor-Verteidigung, welche zu den offenen Spielen zählt.: Philidor was considered the best chess player in the world in his time. The Philidor Defense, which is one of the open games, is named after him.
Er war seinerzeit als Anonymus tätig.: In his time, he was an anonymous writer.

I was a student at that time.
She was playing with her sister at that time.
She was cooking dinner at that time.
He was here at that time.
The Japanese economy was in an unprecedented boom at that time.
He was in America at that time.
I was a high school student at that time.
There were no railroads at that time in Japan.
No one lived on the island at that time.
There were no railroads in Japan at that time.
We were cooking tempura at that time.
I was only a seven-year-old girl at that time.
I went through so unpleasant an experience at that time.
I didn't like beer at that time.
I'm afraid I can't make it at that time.
If my mother had still been alive, she would have helped me at that time.
Napoleon Bonaparte ruled France at that time.
What were you doing at that time?
I was badly in need of his help at that time.
This means that our perception of any situation depends only partly on sensory signals being received at that time.