The “centralist” or anti-provincial group in the General Assembly, led by E. W. Stafford (himself a runholder in the Awatere Valley), secured the passage of the New Provinces Act, largely as a means of weakening the more powerful provinces. This Act made it remarkably easy for any disaffected outlying district to be made into a new province provided the General Assembly were agreeable. All that was required was a petition from two-thirds of the electors in an area of not more than 3 million acres and with a population of not less than 1,000 European civilians. In three instances, Marlborough, Hawke's Bay, and Southland, separation was achieved in this manner by thinly settled pastoral districts. The creation of such small, financially weak institutions helped to discredit and undermine the whole provincial system of government. At the census of 1861 Marlborough had only 2,300 Europeans but enjoyed the full panoplies of independent provincial status.

Provincial politics in Marlborough had a comic opera quality. There were intense personal rivalries, dissension between the small farmer and pastoral factions, and conflicts between Blenheim and Picton interests resulting in frequent changes of the provincial capital (at first Blenheim, then Picton in 1861, then Blenheim again in 1866). At various times there were separation moves in the Picton, Pelorus, and Kaikoura districts, and at other times strong support for re-annexation to Nelson Province. Appropriately, the visible symbols of Marlborough's factious provincialism – the council chamber and departmental offices – were destroyed by fires at Blenheim and Picton within a few months of the abolition of the provinces in 1876.