Good Question! Which would you say?
I’ve just missed the bus, so now I’ll be late.
I just missed the bus, so now I’ll be late.
The answer depends on whether you are speaking British or American English (although either is understood clearly enough by both). I speak American English, so I tend to use the simple past. I would say: I missed the bus, so now I’ll be late. American English favors using the simple past, but if a British person was saying this, more likely the present perfect would be used: I’ve missed the bus, so now I’ll be late. Who is correct?
According to grammar rules, we should use the present perfect tense to talk about an action that happened in the past and has a connection to the present time. The present perfect tense can be identified by the use of have/has with the verb infinitive.
In British English, the present perfect tense is usually used in situations where an action has occurred in the recent past (and the time period is mentioned or understood) and that action has some effect on the present situation. I have just missed the bus (an action in the recent past has occurred), so now I’ll be late (that action has greatly affected my present situation). The focus is on the relationship of what happened and the result thereof.
In American English, it is more common to use the simple past in the same situation. Why is this? The reason centers on the focus of the sentence. In American English the focus is more on the action itself, not on the relationship between the action and the present time. I just missed the bus (an action in the recent past is important), so now I’ll be late (my current situation). Here, the focus is ever so slightly on the actual event that caused the result, rather than the relationship of why the action caused the result.
This difference is slight, but the focus, or main point, is what makes the speaker decide which tense to use in a situation like this. So might be said that the difference really lies in the thought process, not the actual grammar. The key is that British and American English speakers are using different thought patterns, although subtle. This is what makes a difference in what sounds to correct to each speaker.
One must understand that language is not just a matter of grammar rules and vocabulary lists, but a way of thinking. It is these thought patterns in conversation that we hear around us that help us to decide which grammar and vocabulary sounds best. Understanding this makes it easier to grasp a new language. Learning “what sounds right” from what we are accustomed to hearing others say helps us to make decisions of what to say and how to say it much more efficiently than recalling a long and confusing list of rules and dictionary definitions of vocabulary.
True, it could be said that Brits and Americans technically speak the same language, so therefore follow the same rules. However, ask either and they will point out many differences between British and American English. The differences in the sound of the accent, spelling, usage and other stylistic variations are actually rooted in culture. One is not better than the other, rather each has been shaped by differences in geographical distance, historical/political shifts and patterns of thinking.