Why is Winston fascinated with the rhyme about the church bells?

"Oranges and lemons, say the bells of St. Clement's...You owe me three farthings, say the bells of St. Martin's" He cannot remember the rest of it, but knows that the rhyme included the names of all the London churches.

When visiting Mr. Charrington, Winston sees the picture of St. Clement's Dane for the first time. This picture, and its accompanying rhyme, become symbols of the past for Winston. He holds onto this picture, and to the first few lines of the rhyme that Mr. Charrington remembered, believing that they represent his ideal of incontrovertible truth and rebellion against the Party. The Party cannot control this picture, or this poem. Despite the hope Winston places in this object and this rhyme, both foreshadow his downfall. The rhyme ends with the line, "Here comes a chopper to chop off your head," and much later we will learn that a telescreen is hidden behind the picture. Winston's walk through this prole area of the city further confirms his rebellion, and continues to set him on the path towards eventual arrest and defeat.