Any gathering to bid farewell to a major global figure is always a diplomatic dance.

It ripples with tensions. It is embellished by opportunistic gestures of deft bridge-building.

This memorial service for Nelson Mandela was no exception. From among the 100 or so serving and former heads of state or government, it threw together both friends and enemies.

Perhaps the most notable gesture of reaching out, in keeping with Mr Mandela's spirit of reconciliation, came from Barack Obama.

His handshake with Cuba's Raul Castro was perhaps a deliberate seizing of the moment to edge forward the prospect of a thaw in relations between the United States and communist Cuba, after more than half a century of hostility.

Multiple delegations

Also ostensibly in keeping with Mr Mandela's legacy, the current and former presidents of France, Francois Hollande and Nicolas Sarkozy, well known to be rivals, arrived together.

But the bad feeling between them was not entirely effaced. Mr Sarkozy pointedly refused the comfort of a ride on Mr Hollande's presidential plane. And in the stadium, though the two were side by side, they sat stiffly, often looking in opposite directions.

Reflecting the extent of Mr Mandela's iconic influence around the world, many countries sent multiple delegations, made weighty by the presence of former leaders.

Four British prime ministers were there - David Cameron, Gordon Brown, Tony Blair and John Major. It's thought to be the first time for many years that all of the surviving UK prime ministers have travelled abroad to the same event.

In the stadium, however, Mr Cameron was probably relieved not to find himself seated next to Mr Brown and Mr Blair - an awkward photo opportunity avoided.

The United States, too, sent a formidable delegation: three former presidents as well as Mr Obama. George W Bush, Bill Clinton and Jimmy Carter were all there with their spouses - a reflection of the impact Nelson Mandela has made on American as well as African politics.

'Complications'

But perhaps just as interesting were the notable absences.

Mr Mandela's fellow Nobel Peace Prize laureate, the Dalai Lama, did not come. No surprise there. He has twice been refused a visa for South Africa, reflecting the importance South Africa places on not upsetting Beijing. China was represented by Vice-President Li Yuanchao.

From Israel, both Prime Minister Benjamin Netanyahu and President Shimon Peres stayed away - citing cost, security or health considerations.

The real reason, for Mr Netanyahu at least, may have been fears of anti-Israeli protests from inside the large crowd, given Israel's former ties to the apartheid regime and the support the Palestinian cause now enjoys among many South Africans.

Some other leaders also looked as though they stayed away because they were wary of consequences.

Sudan's President Omar al-Bashir decided to skip the event in order to "avoid complications", according to Sudanese diplomats. He is currently indicted by the International Criminal Court.

And neither the new Iranian president nor his genial foreign minister put in an appearance. Tehran sent a less high-profile vice-president.

Following the consternation from conservatives in Tehran at President Hassan Rouhani's phone call to Mr Obama in September, they may well have decided not to risk coming face to face with the US president at the event and being forced into a handshake in front of the cameras, which could cause more problems in Tehran.

Somewhat surprisingly, given the Soviet Union's strong support for the ANC during the apartheid era, Russia sent neither president nor prime minister, but just the head of its upper parliamentary chamber.

Perhaps President Putin was just too busy - he has a state of the nation address to give on Thursday.

He did, however, make time to sign the book of condolence in Moscow and compare Nelson Mandela to Gandhi.

More embarrassingly, Czech Prime Minister Jiri Rusnok was caught on microphone complaining that travelling to South Africa would interfere with his busy schedule and that the thought of going "gave him the shivers".

He subsequently apologised for his comments but the damage was done. Instead, he sent his foreign minister.