Thornthwaite Forest, which lies between Keswick and Cockermouth on the A66 next to Bassenthwaite Lake, includes . Originally most of this land was owned by James Radcliffe, the third Earl of Derwent Water. However, following his execution in 1716, which was as a result of the Jacobean rebellion, both Thornthwaite and Whinlatter was given to the Governors of Greenwich Hospital. They began to stock the area with conifers, mainly Larch, and an old coaching inn was changed into a hospital for diphtheria patients as they believed the clean air and natural environment would help patients to recover quicker. The lengthy tenancy of Greenwich Hospital is reflected in names such as Hospital Fell.
However, James Marshall acquired this land in the 1900’s and immediately began a large scale planting of Larch and Norway Spruce. Unfortunately, during the First World War most of these plantations had to be felled when the nation faced severe timber shortages. The Forestry Commission was set up in 1919, as a direct result of these timber shortages, to rebuild a reserve of timber on a commercial basis today, it is used locally for building materials, pulp for paper and chipboard.
The unique successful breeding programme of ospreys at Whinlatter has attracted over 100,000 visitors to this Forest Park. This Forest Park is also one of the last natural strongholds of the red squirrel in England.