In 1862, an agreement was reached between the Duchy of Cornwall and Lord Brownlow’s trustees (as he was, at that point, still underage) for the estates and park around Berkhamsted, with all its manorial rights, to be sold to Lord Brownlow for the sum of £144,546. The final arrangements were not completed until the following year, 1863, when Lord Brownlow came of age.
At the same time, Lord Brownlow also agreed to rent the ruins of the Castle from the Duchy of Cornwall for a nominal rent. The main bailey was put in order by Lord Brownlow, with the space devoted to local fêtes of all kinds, horticultural shows and archery meetings. A new cottage for the accommodation of guests was also built in 1865 from the fabric of existing buildings on the site.
Today, Berkhamsted Castle remains a possession of the Duchy of Cornwall (two adjoining pieces of land outside the moats are held by the DCMS and Berkhamsted Castle Trust) and proudly retains its historic associations with the Dukes of Cornwall through the centuries.