I am not sure what you mean by introduction, whether you want a general introduction or a literary introduction. Generally, this poem by Philip Larkin provides the interior monologue of a man who stops by a church and considers the history, philosophy and implications of religion. The reader can tell he, himself, is not a regular church goer. The mention of "cycle-clips" indicates he is a cycler who may even be looked at as out of place if the church were having a service. Perhaps this is why he makes sure "there's nothing going on" when he enters. However, the reader comes to find out that this man has tremendous insight into the concept of religion and a society that is perhaps pushing religion aside as a mere relic of history rather than an experience of faith. The speaker is able to put himself into the persona of various individiuals who may have come to the church for various reasons. Ironically, the mind travels of this skeptical man are more philosophical and insightful than what many people consider the new hypocrisy of the church. Through the speaker the reader is made to explore his own feelings of not just a church building but of all that it represents. As the man searches for meaning, so does the reader.