Sir Robert Smirke was the second son of Robert Smirke, a painter who was elected to the Royal Academy in 1793, and brother of Sir Edward (1795-1875) and Sydney Smirke (1798-1877). He was born in London. In 1796 he enrolled in the Royal Academy Schools, and was awarded medals by the Society of Arts as well as the Academy. He was briefly articled to Sir John Soane. In 1805-6 he studied in Italy, Greece and Sicily, publishing 'Specimens of Continental Architecture' in 1806. His earliest buildings after his return, for example Eastnor Castle and Lowther, were medieval in style. However, he soon adopted a classical repertoire, heavily dependent on the Doric or Ionic order, used when he rebuilt Covent Garden (burned in 1856) in 1809. His first project at the British Museum was the construction of the Temporary Elgin Gallery, 1816. In 1823 Smirke was asked to present designs for a new Museum to replace Montagu House, which was not completed until after 1846 when Sydney Smirke took over. A charming sketch by George Scharf I of 1844-5 shows Smirke and "persons employed under him for the rebuilding of the British Museum".
Elected Associate of the Royal Academy in 1808, Smirke became an Academician in 1811. He was Treasurer of the Academy from 1820 to 1850. His knighthood, awarded in 1832, was given for work as one of three official architects to the Board of Works. His design submitted to the competition for the rebuilding of the Houses of Parliament in 1834 was not accepted. His achievements were recognized in 1853 by the award of the Gold Medal of the Royal Institute of British Architects. Smirke retired from practice in 1845 and from public life in 1859 when he left London for Cheltenham.
Thomas Campbell was born in Edinburgh and was apprenticed to a marble-cutter named John Marshall, later transferring to his successor James Dalzell. A patron, Gilbert Innes, Deputy Governor of the Bank of Scotland, enabled him to attend the Royal Academy Schools, where he was admitted on 8 January 1818 as a mature student. He seems to have worked for E. H. Baily around 1817. In 1818, assisted by Innes, he went to Rome, where he had a studio at 12 Piazza Mignanelli by 1824. One of his earliest patrons was the Duke of Devonshire, who commissioned him to execute a statue of Princess Pauline Borghese. Campbell took casts of her hands and feet and later reproduced them in silver and bronze. By 1827 he had become the doyen of Scottish sculptors in Rome. Campbell returned to England in 1830, residing in Leicester Square, although he retained his studio in Rome and returned to Italy to purchase marble. He exhibited at the Academy from 1827 to 1857, latterly from his house in Marlborough Square. Many of his recorded works were for Scottish clients, including the Duke of Buccleuch, for whom he worked in 1847. He is buried in Kensal Green Cemetery.
In 1833 Thomas Campbell contributed £5 towards the purchase of the bronzes of Siris, together with Benedetto Pistrucci (£5), Mr R. Westmacott (£10) and W. R. Hamilton (£20). T. L. Donaldson, in an appreciation of his work in 1858, comments on Campbell's ability to seize "the individual likeness of his sitter" and give the portrait "a sentiment and expression highly characteristic". Whilst criticizing Campbell's lack of imagination, he wrote that he spared no pains to give his works the utmost perfection of finish. Although the marble is heavily veined in one place, the sculptor has made sure that the impurity is not immediately visible, by hiding it at the back. The warm tone of the clothing suggests that Campbell cut away other impurities so that the face appears white and blemish-free. The liveliness of this bust with its carefully carved classical-style drapery, under which is a shirt in a more romantic idiom, is partly achieved by the slight turn of the head and the semi-circular incision for the pupils. The bust is highly polished.