Why did the Sikh empire fall: British design or collapse from within?

The claim: The case that the empire fell from within, and that the British only collected it, rests on the following. Cunningham, who had served as political agent with the army in the field, writes that Lal Singh, Tej Singh and others "felt their incapacity to control the troops" and "considered that their only chance of retaining power was to have the army removed by inducing it to engage in a contest which they believed would end in its dispersion" (p. 285). The Khalsa crossed the Sutlej on 11 December 1845 (National Army Museum), and Cunningham notes that "the river had been crossed, and the treaty broken" (p. 293). Dalhousie's proclamation of 1849 said the British had kept every treaty while the Sikhs had "grossly and faithlessly violated" them (Encyclopaedia of Sikhism).

The sourced facts:

• The killings. Kharak Singh died on 5 November 1840 after "doses of slow poison", and his son Nau Nihal Singh three days later, hurt when a gateway fell on him (the Encyclopaedia says Dhian Singh's men finished him); Sher Singh was shot in 1843. Regiments elected their own panches, which "seriously affected discipline in the army". The Encyclopaedia adds that the British "might have intervened" in Sher Singh's time but were prevented by the Kabul disaster of 1841.
• The British build-up. The Encyclopaedia says preparations for war "began seriously in 1843" under Ellenborough, who told the Duke of Wellington that in November 1845 "the army will be equal to any operation", and that under Hardinge the Ferozepore garrison rose from 4,596 men and 12 guns to 10,472 men and 24 guns. The National Army Museum says "some British officials hoped for war". Khushwant Singh quotes Frederick Currie on 19 January 1845: "if it cannot be Sikh, it must, I suppose, be British." Yet Hardinge wrote on 23 January 1845: "Even if we had a case for devouring our ally in adversity, we are not ready", and asked "on what plea could we attack the Punjab if this were the month of October, and we had our army in readiness?"
• After Sobraon. Khushwant Singh quotes Hardinge: "if I can arrange to make Gulab Singh and the Hill tribes independent, including Kashmir, I shall have weakened this warlike republic." The Encyclopaedia says Hardinge avoided annexation for "political, financial and military reasons", but the treaty of Bhyrowal (December 1846) put a Resident in charge of "the entire civil and military administration", and he pleaded that it was in reality annexation without the disadvantages of direct acquisition.
• 1848 to 1849. The Encyclopaedia says the Multan revolt "may, at the most, be described a local mutiny" which a few regiments could have suppressed, that Gough held back "with a view to letting the trouble spread" and that Dalhousie "allowed the Multan rebellion to spread for five months". At Barrackpore on 5 October 1848 he said "I have drawn the sword, and have thrown away the scabbard". Khushwant Singh quotes his letter: "I can see no escape from the necessity of annexing this infernal country."

The Panthic answer: The Encyclopaedia of Sikhism does not choose between the two. Its entry on the annexation (by B. J. Hasrat) says "Internal dissensions and treachery" caused the defeat of 1846, then that Dalhousie "had meantime prepared the case for the annexation of the Punjab" and that his accusations against the Sikh government "were not sustainable factually". Henry Lawrence, the Resident at Lahore, called the annexation and the deposition of Duleep Singh "unjust and impolitic". Bhai Ajmer Singh argues that the raj was lost through betrayals when it could not have been lost otherwise, and everyone knew it, and that the killings among claimants after Maharaja Ranjit Singh left a conviction that Sikhs are undone from within. After Bhai Maharaj Singh, the last attempt, he says, the Panth settled into keeping silent and getting through the times, and endurance hardened into loyalty. The veterans who gave up their arms in March 1849 took it as an end: one, in Khushwant Singh's account, said "Aj Ranjit Singh mar gaya" (today Ranjit Singh has died).