Brown grabs a golden opportunity

In a keynote speech he plays hard cop on Iran, threatening tougher sanctions, complementing soft cop Obama's offer of new dialogue between Tehran and Washington.

At the same time he offers to reduce the number of British nuclear warheads in the context of multilateral disarmament, which would have seemed a distant possibility a couple of years ago.

Again, Obama's arrival is the spur. Since January he has put out friendly feelers to Moscow in the hope of a thaw in relations after the Bush-Putin chill.

Serious negotiations on nuclear weapons between Russia and the US are needed because the START nuclear arms pact, signed in 1991 just before the collapse of the Soviet Union, expires at the end of this year. George W Bush planned to let it die, believing sanctions and threats could curb nuclear proliferation. Mr Obama believes in old-fashioned agreements.

These are golden opportunities for Brown - which the British leader has lost no time grabbing.

Guess where Obama and Russian president Dmitry Medvedev will meet for the first time? London, at the G20 summit hosted by the ever-helpful Mr Brown.

By putting some (but not all) British warheads on the table, the PM has handed the pair a ready-made breakthrough.

A few weeks ago the special relationship looked doomed to be sidelined. Mr Brown, however, is busily making himself indispensable.