Windsor Castle is the largest and most archaeologically complex secular building in the UK. It is a working Royal Palace, national monument and major visitor attraction. Working as part of the Feilden Clegg Bradley team, Miriam Kelly established the Conservation Plan framework for the castle and authored the chapter on the State Apartments, which have been the historic core of the castle since the twelfth century. The Conservation Plan sets out the evolution and significance of the building, detailing opportunities to reveal or recover significance in the context of continued use. As part of the Windsor Castle Plan for Visitors, Miriam was also involved in detailed designs to extend access for visitors to the medieval heart of the castle.

Two areas of particular focus were the Castle’s Inner Hall and the Undercroft below St. George’s Hall. Both are located within an area of the Castle dating to the mid-14th century, when Edward III turned Windsor from a military fortification into a palace. Throughout the 14th century, the Undercroft served as the castle’s principal cellar, and was adapted under Charles II and again at the beginning of the 19th century as the Servants’ Hall.  Measuring 193 feet (59m) by 31 feet (9.4m), the Plan for Visitors proposed the undercroft as the Café for castle visitors. The Inner Hall was adapted by George IV in the 1820s as a space to receive official guests but was later closed off by Queen Victoria. The Plan for Visitors proposed restoring the Hall and reopening it to the public, reinstating the sequence of spaces linking the visitor entrance on the North Terrace with the State Entrance on the south side and the uninterrupted view across the ground floor of the Castle. From here, for the first time, visitors can see the State Entrance, where royal guests are welcomed to Windsor, and enjoy the spectacular view of the two-and-a-half mile Long Walk, created by Charles II in the 1680s.

Both projects were implemented in 2016 as part of Windsor Castle’s Future Programme, a series of projects funded by the Royal Collection Trust to enhance the visitor experience at Windsor Castle.