and laboratories of the Geological Survey was built to Pennethorne's designs in 1847-9, on a long, narrow site with frontages in Piccadilly and Jermyn Street. It opened in 1851. In 1847 he drew up designs for the Public Record Office in Fetter Lane. A much modified version of the scheme was adopted in 1850, though only portions of it were ever built. In 1848 he modified Nash's Quadrant in Regent Street, removing the colonnade and inserting a balcony and mezzanine story. In 1852 he worked on improvements to Buckingham Palace and the area between St. James's Park and the Royal Mews. His works at the palace included the ball-room, supper-room, and connecting galleries. To the south of the palace he erected the Duchy of Cornwall office, the district post office, and other buildings. Between 1852 and 1856 he completed the west wing of William Chambers' Somerset House. He was responsible for laying out Victoria Park in Tower Hamlets, Battersea Park, and prepared plans and estimates for a proposed "Albert Park" at Islington, which was never carried out. In 1853 he drew up several different ambitious plans for the laying out of the estate owned by the Commissioners of the 1851 Exhibition at South Kensington, one of which included a relocated National Gallery. In the event the area was developed piecemeal, and Pennethorne's contribution to the scheme, in his role as architect to the Office of Works, was a simple "junction" building containing offices and lecture theatre, linking the new iron museum buildings with existing structures, which had been adapted for use as an art school. He was one of the architects invited, in 1862, to submit designs for a memorial to Prince Albert, but his suggestion for a monument in the form of a Classical mausoleum was rejected in favour of George Gilbert Scott's Gothic construction. Unbuilt plans commissioned from Pennethorne included designs for new public offices in Downing Street, and a new War Office intended to be built in Pall Mall. His last work was for the University of London at 6 Burlington Gardens. The adjoining Burlington House, in Piccadilly, had been acquired by the government on his advice, to accommodate the learned societies removed from Somerset House, and the Royal Academy. The plans for the University of London were approved in 1866, but underwent some modification. Pennethorne was knighted, in recognition of his public services, in November 1870.