under the spreading chestnut tree

i was just wondering if anyone knows the signifiagnce of the poem "under the spreading chestnut tree" in the book 1984, i figured it was to do with people betraying each other to big brother and what not but was not quite sure,plaese give your opinion

Here is a good site, that explains, quite in-depthly the meaning behind not just the 'Chestnnut tree' poem, but the history behind the 'Chestnut tree Cafe'.

http://www.orwelltoday.com/readerchestnut.shtml