# Meaning of the sentence "The thieves had run away when the police arrived."

This is from the Quirk's CGEL section 4.24 - The past perfective:

Adverbials of time position, when used with the past perfective, can identify either T2 or T3. Placed initially, they often identify T2:

When the police arrived, the thieves had run away. [11]

But in final position, the interpretation whereby the adverbial refers to T3 is more likely:

The thieves had run away when the police arrived. [12]

Hence in [11], when is likely to be equivalent to By the time that…, but in [12] the when clause is likely to be an answer to the question: 'When had the thieves run away?'

I can only understand the sentence [11], which means that the thieves' running away occurs before the police's arriving, which itself occurs in the past T2. So we use past perfective in the superordinate clause T3, which meets the "past in the past".

Now, I cannot tell the difference between these 2 sentences [11] and [12] even after reading the explanation. I think they have almost the same meaning. Why does it say "But in final position, the interpretation whereby the adverbial refers to T3 is more likely:"?

PS: If the when clause adverbial in The thieves had run away when the police arrived. [12] refers to T3, then what does the superordinate clause The thieves had run away refer to?

The other interpretation, the one that you're apparently missing, is that both actions happened at T3. We normally use the past perfect (representing an event at T3) only with a later past event (at T2). Therefore, presumably some unspecified event happened at T2. Let's say that that event was a shopkeeper's discovery of a burglarized store. Then we might have the following conversation:

Shopkeeper: I arrived at my store this morning only to find the safe empty.
Other person: How terrible! When had the thieves run away?
Shopkeeper: The thieves had run away when the police arrived.

Because both events in the last sentence happen at T3, I'd prefer to put both clauses in the past perfect, but this use of the simple past tense is quite common.

• What's puzzling about the example in Quirk et al. is that to express such an idea without further context you would likely use the simple past: "They ran away when the police arrived." Apr 10, 2023 at 4:31
• The shopkeeper should say The thieves had run away by the time the police arrived. Thus, not an example using English effectively. Apr 10, 2023 at 4:34
• @Xanne The shopkeeper's response is from Quirk verbatim. I agree that it's not the best, as I note in my last sentence. Apr 10, 2023 at 4:37
• @MarcInManhattan Thank you very much. I understand both the sentences now. There is a implicit context setting the past time T2, so both the superordinate clause and the subordinate adverbial one in [12] occur before T2. The thieves' running away still occurs before the police's arriving. Apr 10, 2023 at 8:43
• @kevin4fly: Note that this alternative reading is only really plausible if there is an event in another sentence which takes place after the police arrive and the thieves run away. This other event triggers the past perfect in this sentence. Apr 10, 2023 at 12:02