I found this excellent little arbor under the epicormic growth of a large Lime (Tilia spp). The ground was bone dry even after raining all day today.
It is enclosed on 3 sides and well sheltered. A bed and a fire for warmth or enclose it completely and you have a excellent shelter.
There is plenty of leaf debris for insulation and lime is of course one of the best for friction fire.
In a survival situation a place like this can save you a lot of effort.
Keep your eyes peeled.