A critical case especially where there is a history of seemingly trivial incidents. In finding that sending 3 letters was capable of amounting to harassment, it stresses the importance of looking at the totality of the course of conduct and not at individual events.
Rather than summarise badly, the best thing is to quote directly:
“In my judgment, the Act is concerned with courses of conduct which amount to harassment, rather than with individual instances of harassment. Of course, it is the individual instances which will make up the course of conduct, but it still remains the position that it is the course of conduct which has to have the quality of amounting to harassment, rather than individual instances of conduct. That is so both as a matter of the language of the statute, and as a matter of common sense. The Act is written in terms of a course of conduct: see sections 1(1), 1(2), 1(3), 2(1), 3(1), 7(3). That course of conduct has to amount to harassment, both objectively and in terms of the required mens rea (see section 1(1)(b)). In the case of a single person victim, there have to be “at least two occasions in relation to that person” (section 7(3)(a)), but it is not said that that those two occasions must individually, ie standing each by itself, amount to harassment. The reason why the statute is drafted in this way is not hard to understand. Take the typical case of stalking, or of malicious phone calls. When a defendant, D, walks past a claimant C’s door, or calls C’s telephone but puts the phone down without speaking, the single act by itself is neutral, or may be. But if that act is repeated on a number of occasions, the course of conduct may well amount to harassment. That conclusion can only be arrived at by looking at the individual acts complained of as a whole. The course of conduct cannot be reduced to or deconstructed into the individual acts, taken solely one by one. So it is with a course of communications such as letters. A first letter, by itself, may appear innocent and may even cause no alarm, or at most a slight unease. However, in the light of subsequent letters, that first letter may be seen as part of a campaign of harassment.”