Poem?

[Taberif]

Throughout the second part of the novel, the poem of the different churches is rehersed numerous times.

"Oranges and Lemons, say the bells of St. Clement's,
You owe me three farthings, say the bells of St. Martin's,
When will you pay me? say the bells of Old Bailey,
When I grow rich, say the bells of Shoreditch."

From the text, I gathered that it ends like:

"Here comes a candle to light you to bed,
Here comes a chopper to chop off your head"

My first question is what is the significance of this poem. Is there even one?
It is mentioned quite a few time so i was thinking it may be important.

Second, at the end of part two, the mysterious voice (Mr Charrington) says:

"Here comes a candle to light you to bed,
Here comes a chopper to chop off your head"

Why does he say this? I was thinking it maybe just a little hint to the reader, and maybe to Winston, to who the person on the telescreen is. Any replys are apprieciated.;)

[The Atheist]

I think it's there to counterpoint the difference between before The Party - where it's a harmless nursery rhyme and fun for children to try to "chop off" others' heads as they play the game, with the reality of the Thought Police, where the head-chopping can be a lot less figurative.