Gilbert was born in London on 23rd January 1888. His parents were Arthur Ledward and his wife Mary Jane, nee Wood. Gilbert's father, who died when Gilbert was two years old, was a sculptor and his grandfather was a master potter. Gilbert was educated at St. Marks College, Chelsea until his mother took the family to live in Germany. In 1905, Gilbert enrolled at the Royal College of Art in London.
He won the British Prix de Rome for sculpture in 1913, and in World War I served in the Royal Garrison Artillery and later as a war artist. He was professor of sculpture at the Royal College of Art and in 1937 was elected a Royal Academician. He became president of the Royal Society of British Sculptors and a trustee of the Royal Academy.
Gilbert received commissions for war memorials after the Great War of 1914 to 1918 included the Guards Division memorial in St. James's Park, London, two lions for the Memorial to the Missing at Ploegsteert, commissioned by the Imperial War Graves Commission, and war memorials at Stockport, Abergavenny, Blackpool, Harrogate, and Stonyhurst College (1920), the last of which took the form of a marble altar relief.
Between 1922 and 1925, in partnership with H. Chalton Bradshaw, he created the bronze sculptures for the Household Division's memorial on Horse Guards Parade, Westminster. To the same period belongs his neoclassical marble figure of Britannia for the Hall of Memory at Stockport.
From the late 1920s, he worked less on models to be cast into bronze and more in direct carving of stone, although he made bronze statues of King George V for Kampala, Uganda, in 1939, and for Nairobi, Kenya, in 1940, and another of King George VI for Hong Kong in 1947.
Ledward's portrait busts in marble include those of Bishop de Labilliere (1944), the actress Rachel Gurney (1945), and Admiral Sir Martin Dunbar-Nasmith VC (1947). His war memorials after the Second World War include one in Westminster Abbey to the Submarine Service, Commandos, and Airborne Forces (1948).
Ledward designed the bronze figures of St Nicholas and St Christopher at the Hospital for Sick Children in Great Ormond Street (1952), the fountain in Sloane Square (1953), the new Great Seal of the Realm of 1953 and the 1953 crown for the coronation of Elizabeth II, of which more than five million were minted. In 1957, he created a memorial to the second Duke of Westminster in St Mary's Church, Eccleston, Cheshire.
His last work was a stone frieze with the title Vision and Imagination for Barclays Bank in Old Broad Street, City of London. When the building was demolished in 1995, the frieze was saved from destruction by the Public Monuments and Sculpture Association.