Dianna Patricia Melrose was educated at St Catherine's School, Bramley, King's College London (BA, Spanish & French) and the Institute of Latin American Studies, University of London.

She worked as a Spanish interpreter in the City of London, then briefly for the British Council, before joining Oxfam in 1980.

She was seconded to the Department for International Development (DFID) in 2002, first as head of its Extractive Industries Unit (an initiative by Prime Minister Tony Blair aimed at ensuring that the people of oil-, gas- and minerals-producing countries benefit from the revenues) and then as head of DFID's International Trade Department.

In 2006 she returned to the FCO as head of its EU Enlargement and Southeast Europe group before being posted as Ambassador to Cuba in 2008.

She left Cuba in July 2012 and was appointed High Commissioner to Tanzania in February 2013.