The poem "Funeral Blues" is about loss and grief. The speaker has lost somebody that he loves and is grief-stricken by the loss. At the same time he feels that it is not right that the whole world hasn't come to a standstill to mourn along with him. He must mourn alone and be alone with his grief, as the world carries on as normal.
In the opening line of the poem the speaker proclaims "Stop all the clocks, cut off the telephone." The diction here creates an urgent, perhaps desperate tone. The speaker is desperate for the world to stop so that it can mourn with him, and in so doing mark the loss he is experiencing as significant. The fact that the world does not stop suggests to the speaker that his loss is not as significant as he feels it to be, hence the desperation in his tone.
The urgent, desperate tone of the opening line is mostly created by the verb phrases "Stop all" and "cut off." These are imperative verb phrases, meaning that the speaker is ordering the clocks to stop, and ordering the telephones to stop ringing. The fact that both clauses within the poem's opening line begin with imperative verb phrases immediately lends to the speaker's voice an urgent tone. Within the rest of the opening stanza there are four more imperative phrases, which serve to compound this sense of desperation.
This tone is also emphasized by two other aspects of the opening line. Firstly, the word "all" suggests how desperate the speaker is for the whole world to stop. He feels that every single clock has to stop ticking in order to mark the significance of the loss that he is experiencing. Secondly the fact that there is no connective between the two clauses—only a comma—suggests a lack of fluency or calmness in the speaker's voice. He feels that his orders are too urgent to be calm or measured.