Theme and Rheme vs Given and new Information

For Halliday, the Theme is the elements which serves as the point of departure of the message; it is that with which the clause is concerned. The rest of the message, in which the theme is developed, is the RHEME.
From this definition, it would seem that Theme and Rheme correspond to the classical explanation of the meaning of subject and predicate: the subject is what we are talking about and the predicate is what we say about it.
Halliday argues that the Theme is indicated by its position in the clause. In writing English we signal that an item has thematic status by putting it first, no other signal are necessary. This means that:
"In the South of Italy, garbage has become a serious problem": _In the South of Italy_ is the theme, although it doesn't correspond to the grammatical subject _garbage_.
There is a tendency in English to begin the message from common ground.  Halliday refers to this common ground as Given Information, that is information which is recoverable from the text. What is treated as recoverable may be so because it has been mentioned before but that is not the only possibility. It may be something that is in the situation, like I and YOU, or in the air, so to speak; or something that it is not around at all but all the speakers want to present as Given for rhetorical purposes. The meaning is: this is not news.
On the other hand, Halliday refers to new information as information which is not recoverable from text, stating that what is treated as non recoverable may be something that has not bee mentioned; it may be something unexpected, whether previously mentioned or not. The meaning is: this is new.
In this sentence: I got on a bus yesterday and the driver was drunk --> the driver is Given, because the first clause tells us about a bus and we infer from our knowledge of the world that buses have drivers. The new, and most likely shocking information, is the fact that the driver was drunk.
New information is not necessarily always unknown to the reader --> Even the best plans can go wrong: "can go wrong" is difficultly considered new information, because we know that there is always a possibility that even the most carefully planned things will go wrong. But we have to consider that such as new information, because the writer wants the reader to take note of this possibility.
In Hallidayan grammar, there is a fundamental distinction between the concepts of Theme and Rheme and those of Given and New: although they are related, Given and New and Theme and Rheme are not the same thing. The theme is what I, the speaker, choose to take as point of departure. The Given is what YOU, the listener, already know or have accessible to you. Theme and Rheme are speaker oriented while Given and New are listener oriented.