I �ve found this explanation:After it �s time or high time we use past tense. After high time always. We can say that it is time to leave. It �s time we left. Between the two the difference the second expresses that the correct time has arrived, that it is a little late.
"It �s high time we went". This is quite an unusual structure because it has what looks like a simple past form - "went", the past of the verb "to go." - "It �s high time we went." - What is unusual about this is that this sentence is not talking about the past at all! There are a number of phrases, all using the word "time" where this happens.
We have the example - "It �s high time we went", but you could also say:
- It �s time we went, or
- It �s about time we went
and you can use a continuous form as well:
- It �s time we were going
- It �s about time we were going, and
- It �s high time we were going
The past form in these examples is, I think, the subjunctive form of the verb. The subjunctive is often used when we talk about unreal or imagined situations.
ou can remember the time expressions I mentioned above as fixed expressions and they all have more or less the same meaning. They are quite formal in their use and are stating that it �s time that something happened. A parent might say to a child, for example - "it �s time you went to bed!" Which means "I want you to go to bed".
In the party situation you could say, "let �s go!" - but you could also say - "It �s time we went." You can imagine the person who said that might be looking at their watch and worrying perhaps about catching a train.
And if the situation is a little more urgent, we use the expression "It �s high time" which means it �s very important that this happens now - "It �s high time we left - come on or we �ll miss the train." Or again a parent might say to an older child - "It �s high time you found a job, young man!"
I hope this helps
Thanks so much.