Announcing his Cabinet on 17 December 1962, Field named Smith his Deputy Prime Minister and Minister of the Treasury.
Two days later, R.A. Butler, the UK's Deputy Prime Minister and First Secretary of State, announced that the UK government would allow Nyasaland to leave the Federation.
With Northern Rhodesia now also under a secessionist black nationalist government—Kenneth Kaunda and Harry Nkumbula had formed a coalition to keep the UFP out—and Southern Rhodesia under the RF, the Federation was effectively over.
The Field Cabinet made Southern Rhodesian independence on Federal dissolution its first priority, but the Conservative government in the UK was reluctant to grant this under the 1961 constitution as it knew doing so would lead to censure and loss of prestige in the United Nations (UN) and the Commonwealth.
Indeed, Southern Rhodesia's minority government had already become something of an embarrassment to the UK and it hurt Britain's reputation to even maintain the status quo there.
Granting independence without major constitutional reform would furthermore provoke outcry from the Conservatives' main parliamentary opposition, the Labour Party, which was strongly anti-colonial and supportive of black nationalist ambitions.

Butler announced on 6 March 1963 that he was going to convene a conference to decide the Federation's future.
It would be impossible (or at least very difficult) for the UK to dissolve the union without Southern Rhodesia's co-operation as the latter, being self-governing, had been co-signatory to the Federal agreement in 1953.
According to Smith, Field, Dupont and other RF politicians, Butler made several oral independence guarantees to ensure Southern Rhodesia's attendance and support at the conference, but repeatedly refused to give anything on paper.
Field and Smith claimed that Butler justified this to them the day before the conference began by saying that binding Whitehall to a document rather than his word would be against the Commonwealth's "spirit of trust"—an argument that Field eventually accepted. "
Let's remember the trust you emphasised," Smith warned, according to Field's account wagging his finger at Butler; "if you break that you will live to regret it."
No minutes were made of this meeting.
Butler denied afterwards that he had ever made such a promise.
Southern Rhodesia attended the conference, held at the Victoria Falls Hotel over a week starting from 28 June 1963, and among other things it was agreed to formally liquidate the Federation at the end of 1963.

The Federation dissolved on 31 December 1963 with Nyasaland and Northern Rhodesia both on track for full statehood by the end of 1964, while Southern Rhodesia continued to drift in uncertainty.
Under huge pressure from the RF to rectify this matter and win independence, Field's perceived vacillation and timidness in his dealings with the UK government caused sections of his party to lose confidence in him during early 1964.
On 2 April 1964, with Smith in the chair, the RF caucus passed a near-unanimous vote of no confidence in Field, leading to the Prime Minister's resignation 11 days later.
Smith accepted the Cabinet's nomination to take his place.
He was the first Southern Rhodesian Prime Minister to have been born in the country, something that he thought profoundly altered the character of the dispute with Britain. "
For the first time in its history the country now had a Rhodesian-born PM, someone whose roots were not in Britain, but in southern Africa," he later reflected—"in other words, a white African."
Announcing his Cabinet on 17 December 1962, Field named Smith his Deputy Prime Minister and Minister of the Treasury. Two days later, R.A. Butler, the UK's Deputy Prime Minister and First Secretary of State, announced that the UK government would allow Nyasaland to leave the Federation. With Northern Rhodesia now also under a secessionist black nationalist government—Kenneth Kaunda and Harry Nkumbula had formed a coalition to keep the UFP out—and Southern Rhodesia under the RF, the Federation was effectively over. The Field Cabinet made Southern Rhodesian independence on Federal dissolution its first priority, but the Conservative government in the UK was reluctant to grant this under the 1961 constitution as it knew doing so would lead to censure and loss of prestige in the United Nations (UN) and the Commonwealth. Indeed, Southern Rhodesia's minority government had already become something of an embarrassment to the UK and it hurt Britain's reputation to even maintain the status quo there. Granting independence without major constitutional reform would furthermore provoke outcry from the Conservatives' main parliamentary opposition, the Labour Party, which was strongly anti-colonial and supportive of black nationalist ambitions.
Butler announced on 6 March 1963 that he was going to convene a conference to decide the Federation's future. It would be impossible (or at least very difficult) for the UK to dissolve the union without Southern Rhodesia's co-operation as the latter, being self-governing, had been co-signatory to the Federal agreement in 1953. According to Smith, Field, Dupont and other RF politicians, Butler made several oral independence guarantees to ensure Southern Rhodesia's attendance and support at the conference, but repeatedly refused to give anything on paper. Field and Smith claimed that Butler justified this to them the day before the conference began by saying that binding Whitehall to a document rather than his word would be against the Commonwealth's "spirit of trust"—an argument that Field eventually accepted. "Let's remember the trust you emphasised," Smith warned, according to Field's account wagging his finger at Butler; "if you break that you will live to regret it." No minutes were made of this meeting. Butler denied afterwards that he had ever made such a promise. Southern Rhodesia attended the conference, held at the Victoria Falls Hotel over a week starting from 28 June 1963, and among other things it was agreed to formally liquidate the Federation at the end of 1963.
The Federation dissolved on 31 December 1963 with Nyasaland and Northern Rhodesia both on track for full statehood by the end of 1964, while Southern Rhodesia continued to drift in uncertainty. Under huge pressure from the RF to rectify this matter and win independence, Field's perceived vacillation and timidness in his dealings with the UK government caused sections of his party to lose confidence in him during early 1964. On 2 April 1964, with Smith in the chair, the RF caucus passed a near-unanimous vote of no confidence in Field, leading to the Prime Minister's resignation 11 days later. Smith accepted the Cabinet's nomination to take his place. He was the first Southern Rhodesian Prime Minister to have been born in the country, something that he thought profoundly altered the character of the dispute with Britain. "For the first time in its history the country now had a Rhodesian-born PM, someone whose roots were not in Britain, but in southern Africa," he later reflected—"in other words, a white African."
Ian Smith