Two passages from Rory Stewart’s review of Diana Preston’s The Dark Defile: Britain’s Catastrophic Invasion of Afghanistan, 1838-1842, in the New York Review of Books 8/16/12:
As General William Nott, who commanded at Kandahar throughout the campaign, remarked: “If a man is too stupid or too lazy to drill company, he often turns sycophant, cringer to the heads of departments and is made a ‘Political,’ and of course puts the government to enormous expense, and disgraces the character of his country.” (p. 80)
It is true that, to the fury of military officers like General Nott, the “politicals” who survived could not avoid a knighthood, a governorship, an honorary degree, a medal from a learned society, or even a parliamentary seat, but it was not easy to survive (pp. 80-1)
This is nouning of the adjective political as ‘political person’ — specifically, in this case, as ‘political officer’. Nouning of this adjective, in several senses, began in the 19th century.
OED3 (Sept. 2006) has three subentries for political ‘political person’, shown here with a couple of cites each:
a. A politician; a political writer. [cites beginning in 1833]
1857 T. P. Thompson Audi Alteram Partem II. App. 97 If there is a heaven for politicals, you and I, Sir, will ask for a corner of the Tory bench.
2001 Arizona Republic (Nexis) 21 July b. 6 Your staff writers have depicted the independent politicals as ‘cool’ individuals who will determine future elections.
b. A political agent, officer, etc. [cites beginning in 1841]
1841 Times 2 Aug. 5/4 Numbers of his letters have been intercepted, and the politicals now discover..that his intrigues have been the main cause of all the disturbances in the country.
1898 G. Smith Twelve Indian Statesm. ii. 27 A man of action, whether as a soldier, a ‘political’ in the Anglo-Indian sense, or an administrator.
c. A political exile or prisoner; a victim of politically motivated state harassment. [cites beginning in 1884]
1884 19th Cent. Mar. 488 The chief of the garrison openly says he would be happy if some ‘political’ offended him, as the offender would be hanged.
1888 Cent. Mag. 35 402 Politicals suffering from nervous affections,..are often put in the same ward with insane criminals.
Subentry b is the one we see in the quotations in Stewart’s review. The OED cites for this subsense are all, in fact, from British administrative usage.
[The conflict chronicled in Preston's book came to be known as the First Anglo-Afghan War. It was succeeded by a second war in 1878-80 and a third, brief, war in 1919. And now by the current conflict. The British were not involved in the nine-year Soviet war in Afghanistan, in 1979-89.]