What tree are you talking about, Kildrummy? It is quite common for people to refer to any conifer as a 'pine' tree when it might be something different. If your tree is a larch (google 'larch' for some pictures) then this is decidous and the leaves will fall at this time of the year. If you do actually mean a pine tree then it might have a disease and probably cannot be cured. Do you live in one of the parts of the UK that has had a drought this summer? This could have stressed the tree and led to this condition.