Bossano was born in Gibraltar and has a degree in Economics from the London School of Economics, as well as a degree in Italian from the University of Birmingham. He became part of the trade union movement in the 1960s while working as a seaman in Britain, where he was a member of the British Labour Party. He was asked by a group of Gibraltarian politicians to return to Gibraltar and was elected a member of the House of Assembly in 1972, as a candidate of the Integration with Britain Party. In 1969 the IWBP leader, then the Chief Minister, Sir Robert Peliza, was the mover of the Preamble to the Constitution which safeguards Gibraltar from ever passing to Spain without the expressed wishes of the Gibraltarians. He also became the Branch Officer for the Transport and General Workers Union. In 1975, he left the IWBP to form the Gibraltar Democratic Movement, which won four seats in the Assembly in the 1976 election and two years later became the Gibraltar Socialist Labour Party. He has always kept a hard line stance against any sovereignty deal with Spain without the consent of the Gibraltarians. In 1980 he led a demonstrations of about 2,000 Gibraltarians protesting at the opening of negotiations between Spain and the United Kingdom agreed on the Lisbon Agreement. In 1987 he supported the position of the Government of Gibraltar and the Assembly against any agreement between Spain and the United Kingdom with regard to the joint use of the Airport of Gibraltar. On 10 November, Bossano and Joshua Hassan, then Chief Minister, led a demonstration of about 12,000 Gibraltarians, one of the largest ever held in the territory. In February 1988, Bossano and Adolfo Canepa, the leader of the Association for the Advancement of Civil Rights, stated that the Gibraltar House of Assembly would not approve the :s:Gibraltar Airport Agreement|agreement reached by Spain and UK in December 1987 on the joint use of the Airport unless Spain accepted the British sovereignty over the isthmus. In the key 1988 election, Bossano's party called for the self-determination, expressed its opposition to the negotiations over the sovereignty and future of Gibraltar between Spain and the United Kingdom, and opposed to any transfer of sovereignty to Spain. It also asked for the withdrawal of the negotiations on the Brussels Declaration and opposed to the Airport agreement. The GSLP got 8 seats and a 58.2% of the popular vote. Bossano received a personal vote of 8,1128, about 4,000 more than his contender, Adolfo Canepa. Therefore Bossano was the new Chief Minister. His re-election in 1992 with a 72% share of the vote, caused considerable friction with governments in both London and Madrid who were looking for a solution to the 300-year-old Spanish claim to Gibraltar. As Chief Minister he maintained good relations with Spanish politicians at municipal level, but would not sit to discuss the sovereignty of Gibraltar with them. During his time in office, Bossano also oversaw significant economic change, resulting from the decline of traditional sources of employment, such as the UK Ministry of Defence, and the creation of a private sector economy based on offshore finance and tourism. He broke the back of the severe housing problem existing in Gibraltar before he came into power, by reclaiming land from the sea and constructing hundreds of affordable flats, which were offered at very reasonable prices. For the first time, and since then, Gibraltarians have become home owners, rather than renting from the government, as was traditional. His main quest is and has always been to achieve the decolonisation of Gibraltar through the maximum level of self-government possible resulting in the removal of Gibraltar from the United Nations list of Non-Self-Governing Territories. As leader of the GSLP and the Opposition and following his retirement as party leader, Bossano is still prominent in Gibraltar politics. He stood down as GSLP leader in April 2011, replaced by Fabian Picardo. Bossano remains active in politics and was a GSLP candidate in the Gibraltar general election in December 2011. Upon the GSLP-Liberal victory, Bossano got a seat in the Gibraltar Parliament and was appointed Minister for Enterprise, Training and Employment by the Chief Minister, Fabian Picardo. The GSLP-Liberal government under Fabian Picardo won a second term at the 2015 general election and as of 2017, Bossano held the position of Minister for Economic Development, Telecommunications & the Gibraltar Savings Bank.
