With that change project over and with New Zealand set to begin a two-year term on the UN Security Council in January, it is more likely than not that the job will go to a diplomat or a former diplomat than to another outsider.
Among the names that could be interested in the job will be former diplomat Sir Maarten Wevers although since leaving his job and head of the Department and Prime Minister, he has been involved more in governance work such as chairing the Earthquake Commission.
Another former diplomat likely to apply is Brook Barrington, a former ambassador who went on to become deputy secretary of Defence and is now deputy secretary at the Ministry of Justice.
Current Mfat staffers who may be in the picture include John McKinnon, a former Secretary of Defence, but he is about to take up his second stint at Ambassador to China in January; Chris Seed, the High Commissioner to Australia, Amanda Ellis, New Zealand's ambassador to the Geneva office of the UN; and Deputy Secretary Gerard can Bohemen, a key figure in New Zealand's campaign for the Security Council seat.
Mr Allen said in a statement he was proud of his achievements at Mfat.
"The ministry has been modernized and is in great shape to serve the interests of New Zealand."
It had been a particular highlight to complete his service after the Security Council win.
Foreign Minister Murray McCully said Mr Allen had created a ministry that was more modern and effective.
Labour's foreign affairs spokesman, David Shearer, said putting a non-diplomat at the helm had been "an experiment worth running" but Mr Allen had carried out what Mr McCully wanted which was to down-size foreign affairs significantly.
"Unfortunately that meant that many of the middle tier or people in foreign affairs, the people who are up and coming and promising, left as a result of the restructuring."
It had had a huge affect on the morale at the ministry and its ability cope into the future.
He believed Mr McCully would want somebody again ''to do his bidding and who wont run off independently".