The timing of events is important circumstantial evidence in the employment tribunal. One of the reasons that preparing a chronology is so useful is that it helps you find patterns that support your case.
The classic example of this is a dismissal, where an employee has been dismissed 48 hours after announcing her pregnancy. The tribunal is likely to take some convincing that this is a coincidence. Similarly, if someone makes a protected disclosure and dismissed immediately afterwards. the tribunal will be sceptical of claims that there were long-standing capability problems.
In such cases, you will want to emphasis the timeline of events. Your cross-examination and submissions should draw the tribunal’s attention to the pattern, while undermining the respondent’s attempts to present other explanations.
But this sort of evidence is circumstantial and not definitive. It is a mistake to think that just because one event happened shortly after another, the first event must have caused the second.
If, say, the pregnant employee is dismissed along with 50 of her co-workers and the employer produces compelling evidence of a redundancy situation, much of the probative value of the timing disappears (although you would probably want to look carefully at why she was selected for redundancy).
For math / philosophy geeks, the principle is illustrated below:
Comic by xkcd