Home Truths reporter, Katy Walsh, went out into the wilds of Britain to search for the hidey-holes kids create to escape from their parents.
"You may have had one, I certainly did. My Dad made mine, and it had real windows and a felt roof. It was a wonderful place, I could get away from my parents, and of course they could get away from us. Dens are safe places that grow up with us, as useful for teenagers escaping family pressures as for smaller children sent away to let off steam before tea.
Despite that I had loads of accidents in mine and despite several visits to casualty to get my head stiched up, it was definitely worth it."
Katy first spoke to Francis Owen who visited her Grandmother in rural Wales every summer as a child, and for whom the main attraction was a special hidey-hole within an old rhododendron bush.
The inner branches had no leaves and created a green flowerey cave - the setting for endless games of "house". It also provided a useful base from which to go apple and gooseberry scrumping in the local orchards.
As the eldest of three Francis used to organise games like Dragons "...in which one of us would leap out and try and scare the others. It was better fun that playing sandcastles!"
Deep in Hertfordshire Katy also visited the Mitchell family who showed her their tree house. It is hidden from the house, waterproof, accessible only via a small trap door and contains an old sofa. Grown-ups are strictly not allowed inside - even if they could fit! According to Dad "..the nice thing is that girls use it for their games and the boys use for quite different games. And it is sufficiently far away from the house for the squabbles not to be overheard!"
Mum adds: "Children get stressed just like adults - we've been on holiday for nearly two months and they seem to be relaxed and enjoying each others company - and enjoy playing. they don't seem to want to be doing loads of activity and having friends round all the time - they seem to be quite happy to amuse themselves playing fantasy games within the tree house."