Seven presidents, three of them socialists: González, Zapatero, Sánchez

The Transition started on the day of dictator General Franco's death – November 20, 1975 – and was complete by December 1, 1982.

It was on this date that the first socialist president of Spain, Felipe González, entered the Moncloa Palace – the official presidential residence – with 207 votes in his favour out of the Parliamentary total of 350.

He was re-elected on July 23, 1986 with his own party's 184 votes alone, and again over December 4 and 5 of 1989.

González's fourth reign started on July 9, 1993 and ended on May 4, 1996 when the PP first took up office, led by José María Aznar.

Socialist number two, José Luis Rodríguez Zapatero won a landslide victory in the 2004 elections, gaining office on April 16 and ending Aznar's second reign after the then PP leader fell out of favour for claiming the al-Qaeda bombs which killed 192 commuters on a Madrid train was the work of Basque separatists ETA.

Zapatero, seeing his mandate was weakening, took the decision to call a general election six months early, on November 21, 2011, ending his second term of office.

His alleged denial of the financial crisis until it had fully set in, and the public blaming him for it, was enough to paint Spain blue and give a massive majority to the PP and Mariano Rajoy.

Inconclusive election results four years on left Spain in limbo for nearly a year, with a second general election leading to the same outcome – the PP in a heavily-shrunken minority and the PSOE and emerging independent parties, left-wing Podemos and the centre-right Ciudadanos, as third and fourth forces in Parliament.

A third election – expected to fall on Christmas Day in 2016 – looked a certainty until various minority parties reluctantly chose to back the PP just to give Spain a government and get the budget signed off.

Ciudadanos was key in triggering Rajoy's second term of office, drawing up a 'red line list' including a series of measures for fighting corruption and making this a condition of its support for the PP's candidature.

But the last year and eight months has seen a minority government with a wafer-thin mandate in power, leading to many crucial decisions being stalled or drawn out – including the State budget, which has only just been signed off for this year thanks to the Basque National Party (PNV) voting in favour on condition of State pensions being increased.

Prior to the PSOE's and PP's perpetual electoral musical chairs – which has seen the 'Big Two' taking turns for nearly 36 years – Spain had just two other presidents after Franco's 40-year dictatorship.

The first of these was Adolfo Suárez of the Central Democratic Union (UCD), a multi-faceted coalition – and it was Suárez who led Spain through the Transition, closely aided by the then democratic hero King Juan Carlos I, as well as bravely thwarting an attempted military coup d'état.

Suárez retired from public life in 2003, shortly after his Alzheimer's diagnosis which ended his life in 2014 – by which time, he did not recognise his family, although enjoyed their company, and had completely forgotten he was ever president.

Madrid's Barajas airport was named after him in the year of his death as a tribute.

Suárez's resignation in January 1981 was accompanied by his televised speech concluded with: “I don't want a democratic system of convenience to be, once again, a parenthesis in Spain's history.”

Marquise of Ría de Ribadeo and Grandee of Spain Leopoldo Calvo-Sotelo y Bustelo was sworn in on February 23, 1981, during which an attempted coup was stalled by the outgoing Suárez.

The UCD's Calvo-Sotelo took steps to modernise Spain, approving the divorce law – since marriage annulments were not legal before then – joining NATO and concluding the 17-region model, and changing the national flag to the colours still used today, but his short reign was turbulent and ended with another attempted coup and a general election that put Felipe González in power.

Photograph (L-R): Felipe González, José Luis Rodríguez Zapatero, and Pedro Sánchez