The shadow cabinet is a feature of the westminster system of government. it consists of a senior group of opposition spokespeople who, under the leadership of the leader of the opposition, form an alternative cabinet to that of the government,. The concept of the shadow cabinet comes from the british system of government. the uk parliament website states that it consists of �a team of senior spokespeople chosen by the leader of the opposition to mirror the cabinet in government.. Cabinet and shadow cabinet. the cabinet of the united kingdom is the collective decision-making body of her majesty�s government of the united kingdom, composed of the prime minister and some 21 cabinet ministers, the most senior of the government ministers..