I would certainly agree that where a reporter writes something which the speaker didn't actually say then, provided that the misattributed part is substantial enough, the reporter (or more likely his employer) will be able to claim copyright in that part of an article or news story, which really would be a work of fiction! An example of the opposite of this was the famous remark attributed to Sir Harold Macmillan in 1957: "You've never had it so good". The press handout of the speech actually used the words ".. most of our people have never had it so good", although there is some debate about whether he actually spoke these words when giving the speech itself.
You asked about other caselaw. There doesn't seem to be much which directly relates to this specific aspect of newspaper reports of speeches. However there are a couple of cases involving musical transcription which include many of the same factors. The first is called Robertson v Lewis  RPC169, and it is significant because the judge in the case, Mr Justice Cross, expressed the opinion that Walter V Lane was no longer good law, and that a shorthand writer was not entitled to copyright in a work which was dictated to him/her, or was noted down from an extempore speech. This view was on the grounds that Walter v Lane predated the 1911 Copyright Act (see Section 1) which introduced the word 'original' into UK copyright law. This is significant because of what was said, when the Walter v Lane case went to the House of Lords, by the then Lord Chancellor, Lord Halsbury:
Thus the fact that parliament expressly inserted the word 'original' into the 1911 Copyright Act may be viewed as an intention to reverse the view taken by the Lord Chancellor in Walter v Lane. However, in fairness, there have been other, more recent decisions, such as Express Newspapers plc v News (UK) Ltd*  FSR 359, in which the courts have accepted that Walter v Lane is still good law. But it is worth stressing that at no stage in the Walter v Lane case was the Times newspaper claiming exclusive copyright in the speeches of Lord Roseberry. The copyright claimed was purely in the reporter's written version of the speeches.The Court of Appeal introduces the words "original composition" as if those were the words of the statute [the Copyright Act 1842] ... I am compelled to point out that such words are not to be found in the statute ... The judgment of the Court of Appeal is entirely based on the thing protected being an original composition in the sense that the person who claims the protection of the statute must not have obtained his words or ideas from somebody else, but must be himself an original author in the sense which the word is generally used in respect of literary composition ... The implied proposition is that the only person who could obtain copyright in his speech is the person who spoke it, and that the word "original" must by construction be read into the statute - that the true analogy is the true and first inventor of patent laws. I think the analogy is a false one. I do not find "original" in the statute, or any word which imports it, as a condition precedent, or makes originality of thought or idea necessary to the right
The second music case was Hyperion Records Ltd v Sawkins , where the court, effectively, endorsed the Walter v Lane decision. This was a case about the extensive research and expertise of the musicologist Dr Lionel Sawkins in creating modern playable versions of works by the seventeenth century French composer Michel-Richard de Lalande. Copyright in Lalande's work had lapsed, but Dr Sawkins successfully claimed copyright in his revised version of the works due to his skill and judgement in transcribing and researching the original manuscript versions which were not in the form of modern musical notation.
But as already mentioned in an earlier posting, the Infopaq decision by the CJEU has effectively set a new standard test for originality, namely the intellectual creation of the author. Some authorities claim this has signalled the end of the skill and labour doctrine, others that it has merely refined the test a bit.
* That case had nothing to do with copyright, per se.