In 1899, he organised and chaired a commission to draw up a petition to Queen Victoria, from anti-War politicians and intellectuals of Southern Africa, stressing the seriousness of the impending conflict.
It included key information that was not disclosed to London by the British High Commissioner in South Africa, Sir Alfred Milner, who was intent on taking the Cape to war.
In parliament however, he quickly gained a reputation as a jovial tease, with an uncanny ability to both foment and soothe disagreements in the house – while all the time taking an amused backseat.
His friends and colleagues in parliament gave him the nickname "Baby Molteno", as he was the youngest of his extended family to be politically active at the time.
He even went so far as to act as the legal counsel for the so-called "Cape rebels", successfully defending them from the charge of high treason in a series of high-profile military tribunals set up across the country, over a period of 2 years.
He then joined several other powerful politicians in successfully fighting the attempt to suspend the Cape's constitution, managing once again to bypass martial law and travel to the Imperial Conference in London to do so.
After his first move of supporting an inquiry into the excesses of military rule, he went on to chair a number of committees and was at the centre of the work to re-establish parliamentary governance.
Parliamentary writer Ralph Kilpin found the contradictory Speaker rather amusing, and described in his book, The Old Cape House, how Molteno once firmly silenced disruptive parliamentarians who were roaring with laughter in the backbenches, only to whisper audibly to the culprit as he passed the Speaker's seat later: "You can tell me the joke afterwards" [13] In 1909, at the Prime Minister's request, he joined the South African delegation as legal adviser, and submitted the draft South Africa Act at the National Convention in London.
Nevertheless, when the new Union House of Assembly was created, Molteno, now representing the constituency of Ceres, was asked to take up his office again, having defeated the Transvaal's candidate for Speaker, General C.F.
Here he settled down to write two racy volumes on the political life of the Cape, a collection of rather random trivia and recollections, and a protracted denouncement of Rhodes, Milner and other imperial figures which he claimed was a warning to South Africa of its future direction.
He was also marginally involved in the highly successful syndicate that his family ran on South Africa's agricultural exports, dominated at the time by his oldest brother John.