I have read a sentence including occur in New Concept English, a well-known English reference book focusing on rules of British English. And in order to fully grasp the word, I tried to make a sentence with it, but in the middle, I was greatly confused by the tense.
It suddenly occurred to me that he [is/was] a considerate leader.
Supposing that the truth is he is definitely a considerate manager, and while I was doing something yesterday, the thought slipped into my mind. Which tense is more appropriate? And please explain in detail, thanks!