1852 he became chairman of the Crystal Palace Company, from which he retired in 1855, as well as from the chairmanship of the Brighton line. In July 1852 he was returned to parliament in the liberal interest for the Wick district, which he represented until 1857 (when he lost his seat for opposing British intervention in China). He was re-elected in April 1859, and was financial secretary to the treasury from the following June until October 1860. In that month he was appointed to the important post of financial minister in India, on the council of the governor-general, to replace James Wilson (1805-1860) [q. v.], who had died within a year of taking up this newly created and lucrative office [see Frere, Sir Bartle]. When first asked to go to India, Laing said to Palmerston, 'You want me to go to India to doctor a sick budget with a deficit of six millions ; that is a question of military reduction, and the possibility of military reduction depends on peace. Tell me candidly what you think of the prospects of peace, that I may regulate my financial policy accordingly.' Palmerston replied, 'I do not trust the man at the Tuilleries an inch farther than I can see him ; but for the next two or three years, which is enough for your purpose, I think we are fairly safe of peace ; therefore go in for reduction.'
Having effected the objects of his mission upon the lines laid down with such conspicuous ability by Wilson, Laing was again elected M.P. for Wick in July 1865. He was rejected for that constituency in 1868, but was returned for Orkney and Shetland in 1872, and sat without interruption until he retired from parliament in 1885. Though a staunch liberal, he was opposed to what he considered the anti-imperialist leanings of Gladstone ; he published in 1884 a careful and moderate indictment of what would now be called Little Englandism in 'England's Foreign Policy.'
In 1867 Laing was reappointed chairman of the London, Brighton, and South Coast Railway (a post which he held down to 1894), and his position as a railway magnate introduced him to the city. Laing's connections with the financial world were not unimportant. During his tenure of the chair at the board of the London, Brighton, and South Coast Railway, that company gradually became highly prosperous, and he contributed to the result not only by his business capacity, but by his skill in choosing and supporting good subordinates. Noting the constant growth of Brighton and other south-coast towns, he was one of the earliest to discern that the line had a great future before it. His confidence was more than shared by a number of London stockbrokers who lived down the line, and knew, or thought they knew, a great deal about it. Hence the enormous amount of speculation that took place for a long period in Brighton Deferred Stock ('Brighton A's'). When speculative operations for the rise turned out well, their authors naturally regarded the management of the line with approval ; but when they did not, Laing came in for more than a fair share of abuse. He was connected with two other important companies in which his knowledge of railways was useful. These were the Railway Share Trust and the Railway Debenture Trust, which, as chairman, he conducted with a much greater degree of prudence than became common as enterprises of this kind multiplied.
It was not until he had turned seventy and retired from parliament that Laing came before the public prominently as an author. His 'Modern Science and Modern Thought' appeared in 1885 and was very widely read, being in fact an admirable popular exposition of the speculations of Darwin, Huxley, and Spencer, and the incompatibility of the data of modern science and 'revealed religion.' A supplemental chapter to the third edition (1886) contained a fairly crushing reply to Gladstone's defence of the book of Genesis. It was followed by 'A Modern Zoroastrian,' 1887, 'Problems of the Future, and other Essays,' 1889, 'The Antiquity of Man,' 1891, and 'Human Origins,' 1892, all written in a similar easy and interesting style. Without possessing in themselves any great scientific value, these works showed Laing's reading, especially in anthropology, to have been extremely wide, and furnished people with general ideas onsubjectsof importance which, if discussed in a less attractive form, would probaby have passed unheeded.
Laing died, aged 86, at Rockhills, Sydenham Hill, on 6 Aug. 1897, and was buried on 10 Aug. in the extramural cemetery, Brighton. He married in 1841 Mary, daughter of Captain Cowan, R.N., and left two sons and three daughters. His personalty was sworn at 94,643l. (Railway Times, 18 Sept. 1897).
Laing's writings are remarkable as the relaxations of a man who had spent over half a century almost exclusively immersed in affairs. He never attained to quite the same thoroughness and grip of his subject as his father, but he had much the same gift of lucid exposition, and the same freedom from self-consciousness or affectation. Besides the works already mentioned and some pamphlets 'Samuel Laing the younger' published:
