The meeting, involving the President, the British high commissioner and World Bank officials, has been kept quiet because a no-show by Mr Sankoh, who has failed to materialise before, would send a deeply negative signal at a crucial time.
The week-long hostage crisis, in which five British military observers were among more than 40 people held captive in the jungle by a rebel group, forced rivals into a dialogue.The information minister, Julius Spencer, said: "What happened was a blessing in disguise and everybody has been able to express their commitment to making the peace agreement hold." Signatures, including Mr Sankoh's, were put to a peace accord in the Togolese capital, Lome, on 7 July. The deal is intended to end eight years of violence, which has left up to one-third of the population displaced and tens of thousands dead or mutilated by machete or axe.
Many people view the agreement as iniquitous. Britain, the former colonial power, heartily supports it. Britain has spent millions of pounds on the country's weak President, Ahmed Tejan Kabbah, elected by the people in 1996.
Through costly military support, it ushered him in, then spent money on keeping him there; and it even helped to restore him to power after a 1997 coup.
In the end, prompted by cost considerations and war-weariness among those Britain and the United States were arming, chiefly Nigerian forces who lost thousands of men, London decided that the rebels could not be beaten on the battlefield.
In March, the Foreign Secretary, Robin Cook, told President Kabbah that, like it or not, he would have to do business with Mr Sankoh's Revolutionary United Front and his ilk. At that stage, the rebels controlled three- quarters of the country, and they still do.
The deal gives rebel groups seats in government and virtual control of Sierra Leone's extraordinary mineral wealth, unparalleled in the world considering that the country is the size of Scotland.
Many Western diplomats accuse Britain of treachery. One said: "After pouring money into supporting Kabbah, Britain decided enough was enough at the worst possible time for him. At some stage it was going to be necessary to make a deal with the rebels, but it should not have been when Kabbah's government had lost control of most of the territory and was in a weak negotiating position.
"Nor should it have been when there were, as there are now, at least seven fighting factions."
The deed is done and Britain is still here, foremost among countries and institutions trying to make the deal work. Sierra Leoneans' desperation for peace, could just be enough - if Mr Sankoh turns up today.
Britain has pledged pounds 8.5m, some of it spent already, and the World Bank is looking to spend about $9m (pounds 5.6m). But the entire process is proceeding grindlingly slowly - there is not even national radio station in Sierra Leone with the transmitter capacity to broadcast news of the peace, let alone reconstruction, to the largely illiterate four million population.
The kidnapping of the Britons and others may have come about partly because the rebel group involved, the Armed Forces Revolutionary Council, lacked information about its future place in government. In this atmosphere of chaos, more needs to be done, more quickly. And Mr Sankoh needs to leave the comfort of his Togo hotel and roll up his sleeves with the rest of them.