This is a very apposite quotation that we can apply to Philip Larkin. What he is famous for is the way his poetry deals with colloquial language of the United Kingdom. In some poems, he even uses swear words. His poetry, because of this, is instantly accessible and the use of plain language shows how he believed in the value of tradition and a suspicion of modern technology and advancements. Such an approach allows Larkin to really be identified with by the people of Britain. His cynical bleakness that make up so much of the tone of his poetry captures the imagination of a post-World War II population that found their country and their prestige greatly reduced. Thus we can safely say that Larkin was a poet for the "common man" through the way that he appealed to the everyday citizen of Britain through his diction and style.
However, we can also clearly argue that he was an "uncommon poet" in his ability to reach out to all sectors of society and remove poetry from being the possession of the well-off and educated. Larkin speaks from his own viewpoint in a number of his poems, and yet each and every one offers unique and novel reflections on the essential human condition, isolation, loneliness and religion. You have only to look at a poem like "Church Going" or "Whitsun Weddings" to see that, in the midst of his accessible language and style, Larkin offers profound philosophical comment. It it these two aspects coupled together that make him unique.