Note to himself: change into your suit at the end of a flight - not the start.
The gaffe was likely a result of the thirty hours of travel, or just the excitement of it all.
It came in his first words at a press conference after meeting Tusk, when English referred to himself as a "recently elected" Prime Minister. He then remembered himself and hastily corrected it to ''recently selected'' Prime Minister since his ascendancy was courtesy of his caucus colleagues rather than the voters.
Otherwise his first meetings appeared to go well. His primary goal was to try to ensure New Zealand did not become collateral damage as the results of the Brexit vote played out. His related goal was to try to position New Zealand well for trade talks with both.
The colourful European Commission president Jean-Claude Juncker put on the entertainment. First came the music to English's ears - Juncker put the rather optimistic timeframe of two to three years on hammering out a free trade agreement between New Zealand and the EU. It is optimistic because Canada's took a decade.
There was also a long tale of how Juncker and English had met in the past but neither remembered it. "And that was a great moment in the history of our relations because it was the first time we met. But this time we really met."
He spared English the affectionate face slaps he has been known to greet other world leaders with, but did escort him away afterwards with much shoulder clapping.
English also got the honour of being the first leader to grace the stage at the controversial "Egg" - the nickname for the new European Council headquarters, known more formally as Europa Building.
Its $485 million cost was criticised in 2012 by former British PM David Cameron given the EU countries at the time were still reeling from the global financial crisis.
English managed to swallow his likely instinctive ex-Finance Minister response and wisely decided flattery was a wider option, so praised its beauty rather than pondered its cost. He's learning fast.
Bill's European Diary
• What Bill English did overnight:
2017 marks the centenary of many of the battles of the Western Front in World War I. English visited the sites and memorials near Ypres, including Messines and Passchendaele where 700 New Zealand soldiers were killed - the most in any battle in its post-1840 history.
• What's on for tonight?
English will meet Belgium's PM Charles Michel. Like English, Michel entered politics at a young age - he became PM when he was 38.
Both are also literature buffs. But English will be hoping not to share another of Michel's experiences: he was once pelted with chips and mayonnaise - a Belgium dish - by way of protest against austerity measures.
English will also meet Nato Secretary General Jens Stoltenberg, who was Norway's Prime Minister in 2001 and again from 2005 to 2013 - showing a similar capacity to English for rising twice.
But the talks tonight are expected to centre on security issues in the wake of terrorist attacks around Europe - Stoltenberg was PM during the attacks in Norway by Anders Behring Breivik, including the bombing of Stoltenberg's own office and a shooting spree on Utoya Island.
English will also meet the third of the European Union's so-called "three presidents'' - European Parliament President Martin Shulz.
As well as trade, English and Schulz could discuss New Zealand's proposed changes to foreign trust laws - an issue that has concerned the European Parliament.
The Parliament was investigating the robustness of other countries' foreign trust regimes in the wake of the Panama Papers. New Zealand had been named as one of the countries being investigated and the Government has now moved to tighten those rules.
