Prepositional Phrases (PP) perform a variety of syntactic functions in a conventional sentence, and cause severe problems to computer systems that automatically analyse the sentential syntax. A major issue in this area has been the automatic determination of the syntactic functions of PPs. Most work published so far makes use of the probabilistic approach, and attach PPs to either the antecedent noun or verb phrase. Due to the natural limitation of the probabilistic approach, it is important to evaluate the linguistic behaviour of prepositional phrases and propose qualitative solutions to the problem. In this article, I first provide a detailed account of statistics regarding the frequency of use for (i) types of prepositions, (ii) syntactic categories as realisations of prepositional complements, and (iii) the syntactic functions of prepositional phrases. Statistics reported here all derive from a representative corpus of contemporary British English. I then describe a set of rules that has been implemented in order to label PPs automatically for their syntactic functions. I finally report on the coverage of these rules empirically observed in an experiment which involved a set of naturally occurring PPs as test data.