Grade I listed buildings in England completed in the 20th century

In England buildings of particular architectural merit and/or historic significance are given statutory protection under the listed buildings scheme. The scheme categorises buildings in three grades; Grade I, the highest grade, Grade II*, and Grade II, the lowest grade. Approximately 500,000 buildings in England have listed building status, the vast majority at Grade II. Decisions on listing are made by the Secretary of State for Culture, Media and Sport, on advice from Historic England, the agency with responsibility for the historic environment. Decisions on listing are closely related to the age of the building. Buildings constructed before 1700 will almost certainly be listed and many constructed between 1700 and 1850 will be. Construction dates between 1850 and 1945 will reduce the likelihood of listing, and even greater selectivity is exercised for post-war buildings. There is a presumption against listing buildings that are less than 30 years old. This approach has seen a relatively small proportion of buildings dating from after 1901 receiving listed status, and even fewer, the highest listing designation, Grade I.

Grade I listed status has been given to 113 buildings completed in the 20th century. Of these, there are twenty-four cathedrals, churches and chapels, nineteen war memorials, seventeen houses, seven memorials, seven university buildings and seven office blocks, four art and museum galleries, three apartment blocks, three military installations and three bridges, two telescopes, two sets of gates, two factories, two animal enclosures and a range of other structures including an orangery, a clinic and a concert hall. Of architects whose work has been listed, the most prolific is Edwin Lutyens, with twenty-one structures to his own account, and two more in partnership, the gardens at Hestercombe House with Gertrude Jekyll, and Middleton Park with his son. Lutyens is followed by Arne Jacobsen, with six buildings at St Catherine's College, Oxford including England's only Grade I listed bike shed. The Modernist Berthold Lubetkin has five buildings on the list, two in conjunction with Ove Arup, who is individually represented by his Kingsgate Bridge in Durham. The Scott architectural dynasty is represented through four ecclesiastical buildings, St John the Baptist Cathedral, Norwich by George Gilbert Scott Jr. and John Oldrid Scott, and three by Giles Gilbert Scott. Robert Lorimer has three war memorials, while Aston Webb also has three structures, all sited at either end of The Mall in central London. Robert Atkinson, William Bidlake, George Frederick Bodley, Ninian Comper, Charles Holden, Goscombe John, Temple Moore, Basil Spence, Owen Williams and Edgar Wood have two buildings each. The engineer Charles Husband designed the two listed telescopes at Jodrell Bank Observatory, the first in partnership with Bernard Lovell. The architects of the two listed military workshops at RAE Farnborough are unknown, while Bob Creer of the Air Ministry is credited with the Operations Room at RAF Uxbridge.

The most recent building to be designated Grade I is Colin St John Wilson's British Library, constructed between 1982 and 1999. The newest designations are for the Sainsbury Wing at the National Gallery, the only work in Britain by Robert Venturi and Denise Scott Brown, which was listed in May 2018; and The New House at Wadhurst Park in Sussex, a private house by John Outram for members of the Rausing family, which was listed in July 2020. Between 2014 and 2018, the First World War Memorials Programme, run by Historic England in commemoration of the centenary of the First World War, saw an increase in the number of Grade I listed structures, with the listing of some 2,500 additional war memorials, and the upgrading of a number of previously listed memorials to the highest, Grade I, designation. There are, as of December 2023, no buildings completed in the 21st century which have been awarded Grade I listed status.

Listing
A listed building is a structure of particular architectural and/or historic interest deserving of special protection. Such buildings are placed on a statutory list maintained by the historic environment agency, Historic England. Buildings are categorised under one of three grades, in descending order of importance:
 * Grade I: buildings of exceptional interest.
 * Grade II*: particularly important buildings of more than special interest.
 * Grade II: buildings that are of special interest.

Listings are formally decided by the Secretary of State for Culture, Media and Sport, on the advice of Historic England, on the basis of a building's architectural and/or historic merit. The specific criteria for listing include:
 * Age and rarity: The older a building is, the more likely it is to be listed. All buildings erected before 1700 that "contain a significant proportion of their original fabric" will be listed. Most buildings built between 1700 and 1840 are listed. After 1840 more selection is exercised and "particularly careful selection" is applied after 1945. Buildings less than 30 years old are rarely listed unless they are of outstanding quality and under threat.
 * Aesthetic merits: i.e. the appearance of a building. However, buildings that have little visual appeal may be listed on grounds of representing particular aspects of social or economic history.
 * Selectivity: where a large number of buildings of a similar type survive, the policy is only to list the most representative or significant examples.
 * National interest: significant or distinctive regional buildings; e.g. those that represent a nationally important but localised industry.

As a consequence of the first criterion, buildings constructed after 1901 comprise a small proportion of the total number of listed buildings. Of those that are listed, even fewer are given the highest, Grade I, designation.

Grade I listed buildings completed in the 20th century

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