All that is well and good, but doesnt explain the interveiw given on channel 4 by a protestor who confirmed that "many people" (her words...) left at night.
Because many people do leave at night.The tents are provided by the organisation as a whole. People sign into them each night if they are staying. But a large amount of protesters go home. Much the same way many go to work during the day. Some people are in poor health and can't stay overnight. And finally there simply isn't room for everyone. Estimates put daytime protests at around 1000 people while about 250 stay overnight. Using the accounts from the protesters, that's around 75% of the tents taken. They probably couldn't house more than 500 people at night without serious overcrowding or expansion. Which is hard because there isn't really much public land in London to occupy like this.
This is how longer term protests and occupations work. People come and go so that there is a constant presence. The occupiers have said they are planning so they could stay for months if possible and necessary. Not many people will be able to actually stay on site till Christmas, but for a well designed and maintained camp keeping a presence till then is entirely possible.
EDIT: That article reminded me of something;
Last week, on Have I Got News For You, MP Louise Mensch asked why the occupiers, if they hated capitalism so much, bought coffee from Starbucks.
Well, for one thing they needed access to some sort of hygiene facilities. Under UK law they were only required to be provided with portable toilets when the police kettled them, and those were taken away later. Then there were problems once they secured new ones thanks to
St Paul's utterly inconsistent stance on health and safety. During the day they make do with public facilities in the area, including those at local businesses.