One in three homeowners admit they regularly 'spy' on their neighbours, it emerged yesterday.
And nearly half say they peek from behind the curtains whenever they hear 'goings-on' in their street.
Almost 50 per cent of people surveyed said they could recite the times their neighbours leave and return from work and spot a new car immediately, with a fifth noticing if a stranger visits.
Noticing parcels being delivered, if a couple argue more than normal or even when the online shopping comes, were other common aspects people knew about those living close by.
But one in ten admit they had been caught peering through the windows by their neighbour.
The study of 2,000 adults – commissioned by Yale as part of National Home Security Month – found that the most common reason given for keeping tabs on the neighbours was 'to check they are all right'.
For neighbours even the intimacy of a relationship is common knowledge - over a quarter knew a neighbouring couple were having real troubles and one in ten even know a neighbour currently having an affair.
Nigel Fisher, from Yale, lead sponsor of National Home Security Month, said: 'This shows just how closely the people who live next to us are watching and the things that don't go unnoticed.
'However, the results show that where people did admit to keeping tabs on a neighbour it was usually with good intentions of making sure everything's alright.'
The study also saw a quarter of people confess to spying on the neighbours at least once a week.