Leading article: Mr Brown spoke with a new voice in Washington

His visit could herald a new relationship between Europe and the US

Whoever had the bright idea that Gordon Brown should address a joint session of the US Congress after his first meeting with America's new President did both the Prime Minister and Europe-US relations a greater favour than perhaps they knew. Mr Brown's affection for the United States is well known and of long standing. But it is something he was well-advised to play down at home so long as George Bush was president and he needed US improvidence to blame for the spreading financial crisis.

Yesterday, Mr Brown's many years of visiting Washington and holidaying on Cape Cod came into their own. He understood his audience, and its idiom.

Tony Blair, it was said, would be a hard act to follow. Silver-tongued and a natural performer, he endeared himself to US audiences as the all-round ally and quintessential Briton abroad. For this, he was lionised; Americans hung on his every word. He made Prime Minister's Questions required viewing among Washington's political classes. How could Mr Brown follow that?

Rightly, he did not try. Awkward in more personal settings, such as the faux informality of the Oval Office the previous day, Mr Brown has always seemed more comfortable behind a lectern. The son of the manse has rarely seemed more comfortable than he did at the pulpit of Edinburgh cathedral, when he gave the oration for Robin Cook. It was something of the same seriousness and affinity with his audience that he took to Capitol Hill yesterday.

But Mr Brown also offered his audience something else: optimism. We have often asked why Mr Blair was so much more effective an advocate for Britain's membership of the European Union when he spoke in Brussels or Strasbourg. Why could he not show the same conviction at home? We could ask something similar of Gordon Brown. After personifying a period of deepest gloom in Britain, Mr Brown yesterday borrowed some of the incorrigible optimism that distinguishes Americans – and played it back to them. We are long overdue for a little of that hope over here.

He was rewarded with a measure of respect and warmth that must have come as a pleasant contrast with the weekly lacerating he has suffered in the Commons in recent months. In terms of atmospherics, Mr Brown's speech did much better than break any residual ice left from the Bush years, it set the tone for a new, more cordial and consensual age, not just in bilateral relations, but – as Mr Brown made a point of saying – between the United States and Europe.

The key to the change, of course, as Mr Brown remarked at the outset, was the overwhelming US vote in favour of Barack Obama. That made possible not only the new mood, but the possibility of talking hopefully, as the Prime Minister did, both about prospects for a new climate change agreement at Copenhagen and about joint action to mitigate the effects of what is now, wherever blame lies, the global crisis.

Mr Brown's ambitions for the G20 summit may be unrealistic. He sang a rather different song yesterday about the virtues of markets from the one he once sung as Chancellor. They should, he said, be "free, but never values-free". Risks should never be separated from responsibilities. But it is the same song that Mr Obama sang in the latter stages of his campaign and one that resonates in Europe. It is too soon to forecast what the G20 might produce. But if, as it seems, there is more transatlantic goodwill today than yesterday, Mr Brown's Washington trip was a success.