Diplomatic sculptor: Solana "modelled impressive things out of the smallest pieces of clay". Photograph: Council of the European Union

For a man who bestrode the transatlantic scene for more than twenty years, not only as EU foreign policy supremo and NATO secretary-general, but as one of Spain’s most important post-Franco politicians, Javier Solana’s retirement on December 1 passed off remarkably quietly. At the press conference where his successor Catherine Ashton was introduced to the world, Solana’s name was barely mentioned. It called to mind the exclamation from the balcony of Buckingham Palace on the death of the last British monarch: “The King is Dead. Long live the Queen.”

Some analysts gave a downbeat assessment of Solana's ten-year term, saying he had been “reduced” to being a mere administrator of small-scale missions. Others honoured his tireless diplomacy, for example over Iran’s nuclear programme or the Middle East Peace process, but said little about any concrete achievements.

Adding insult to injury, the EU-China summit – Solana’s last official act in office – was the most confrontational in recent memory. It lasted under two hours and seemed calculated to snub the EU and, by extension, its international representative. If the Union’s top diplomat ever imagined his own retirement –- and some say he is too energetic, even at 67, to have done so before the very last moment – it is not likely to have looked like this.

To many EU analysts, Javier Solana’s final days invoked mixed feelings. On the one hand, his list of accomplishments is long: 23 European Security and Defence Policy missions, a de facto military headquarters, common policies on a range of foreign affairs issues from weapons proliferation to conflict prevention, and a clear EU role in dealing with one of the world’s most important security problems, Iran’s nuclear programme, as well as Ukraine’s transition. Much of this was not thought possible just a few years ago and owed a lot to Solana’s legerdemain.

Even without the Iraq war, which almost sunk the idea of a common EU foreign policy in 2003, this is an impressive list; taking into account the US-led invasion, the accomplishments look even greater. To think that Solana persuaded EU governments to adopt a European security strategy a few months after the US-Iraq war is simply astonishing.

On the other hand, many would argue that Solana’s policy record is more mixed. What often looked like great diplomatic successes turned out later to be pyrrhic victories. “Solania”, the name given to the improbable and short-lived Union of Serbia and Montenegro forged by the EU diplomat, is one example. In neighbouring Bosnia-Herzegovina, Solana’s pressure to close the Office of the High Representative, which was created when the Balkan war ended, undermined his own envoys and complicated the international engagement in the war-torn country.

But for every critic there are at least two who swear their loyalty to the Spaniard, who admire his avuncular air, which has become a trademark of his diplomacy, and respect his ability to spot mistakes and add important new ideas even after proposals have gone through numerous committees and layers of bureaucracy. In response to Solana’s critics, who think the Council Secretariat was run too informally, there is a simple, incontestable fact: since he took office in 1999, numerous institutions have emerged or were strengthened, from the expansion of the Council Secretariat to the creation of the European Defence Agency. He did not conjure things up out of nowhere, but he did model impressive things out of the smallest pieces of clay. When Solana moved unhurriedly, it was often because large EU governments were pushing him in different directions, particular when it came to personnel matters.

If Solana did not always get the credit he deserved (but often the brickbats he did not) it may be because much of his diplomatic work took place behind the scenes and away from the cameras. He played a pivotal role in the Orange Revolution and contributed greatly to securing Ukraine an IMF loan, when the country was about to default. Though Solana did not in the end succeed in halting Iran’s nuclear enrichment programme, he spent literally thousands of hours trying. One of his achievements was pushing Macedonians and Albanians to make peace in 2001. Participants in the Lake Ohrid talks today admit that it was his interventions, personifying the EU, which pushed them to a deal.

Transfers of power are always brutal to those who are actually leaving office. One day you bestride the world; the next you have to carry change for the taxi. A retiring or defeated US president has almost two months to get used to a new life. But for various reasons, the EU seems to have taken on the British tradition of sending a removal van into 10 Downing Street minutes after the governing party has lost an election. In this haste, it is worth recalling how far the EU has come and how much is owed to Javier Solana. He may leave office without a doctrine to his name. But however well Catherine Ashton does in the job, his departure has brought to a close an era of EU cooperation that many may soon look back on with nostalgia.