That sentence is an example of a participle phrase. In this case, it's a passive participle in the past tense. The subject of the phrase is "a dock strike." The participle is passive because the action of the verb's participle was done *to* the subject (the dock strike was declared), rather than *by* the subject (the dock strike declared). It's important to realize that the reason for the presence of the auxiliary verb been (from "to be") is that it is a passive. That has nothing to do with the tense. For example, both of these sentences have examples of participle phrases in the past tense: The dog, having attacked the cat, ran away. (ACTIVE PAST PARTICIPLE) The sausage, having been attacked by the dog, was wounded. (PASSIVE PAST PARTICPLE) Hope this helps! Let me know if you have questions.

Paulette's right - it's a participle phrase. The useful thing about them is that they don't need to follow rules for tenses.

We need SuKi here Maybe she'll help To me, first, "having been declared" isn't really being used as a verb here. It is used to describe the strike, not as an action on its own. The whole sentence would be something like."a strike having been declared last night, the workers did not come to work today." The verb here is "did (not) come." I can't write a sentence with "having been declared" as a verb. "Having been" is the description of a state of being, not an action.

It is the perfect form of the past tense.