Here is unfinished business. The British created the enormous country of Sudan out of a bundle of geographical regions, and bequeathed one of the world's longest civil wars, which was only brought to a grudging halt in 2005.
Sudan is one of the most bitter and painful legacies of Britain's empire in Africa. This Christmas and New Year while millions enjoy their holidays, the Sudanese will anxiously await the 9 January referendum, which is widely expected to create a new African country when the southern Sudanese vote for secession.
This new country will be one of the poorest on the continent. As many activists point out, a south Sudanese girl has more chance of dying in childbirth than she has of finishing primary school. The entire south has few paved roads, and agriculture and markets are desperately underdeveloped. Food is imported from neighbouring countries, ensuring higher prices. For several decades, aid in the south has primarily been a matter of averting humanitarian catastrophe. Only since the comprehensive peace agreement in 2005 has it been possible to invest in longer-term economic development.
But the anxiety among many close observers now is a return to war rather than poverty. International Crisis Group has been warning of a slide into violent break-up over the last year.
None of the signs have been good in recent months, with acrimonious disputes flaring up between the Sudanese government and the Sudan People's Liberation Movement (SPLM), and public statements becoming increasingly confrontational, according to one of the most experienced observers of Sudan, the Rift Valley Institute (pdf)
Several key technical issues have yet to be resolved, the most important being border demarcation. If secession goes ahead, the border between north and south Sudan will be the longest - and probably most contested - of any in eastern Africa. What makes it even more dangerous is that vital oil-producing areas lie in these contested borderlands. A lot of concern is focusing on the region of Abeyi, where there have already been violent confrontations.
Who should register to vote in these areas? For example, in Abeyi, the north is insisting that the nomadic Misseriya people be allowed to register even if they are only resident during the dry season; the south is arguing that the permanent resident population be included.
Rebecca Tinsley of the human rights organisation Waging Peace is concerned that the dispute along these borders is part of a much wider picture of conflict along the southern edge of the Sahara as land degradation expands the desert south and forces nomadic Arab groups into more southerly areas dominated by black African farming communities.
It's a faultline across Africa that could seriously exacerbate the political issues around secession.
Recriminations are flying back and forth between Khartoum and Juba. Both accuse the other of failing to make the unity since 2005 appealing to the south. The north is making threatening remarks, which are ratcheting up tension and rumours. In an interview with my colleague Simon Tisdall, the Sudanese ambassador in London warned that if the referendum was not carried out properly, "we would not accept it, we would reject it".
Many fear that the elections earlier this year, which were regarded as flawed, do not bode well.
There are also concerns that Khartoum has succeeded in getting through measures which could derail the referendum. It has insisted that at least 60% of registered voters must vote for the result to be quorate, a difficult percentage given the lack of transport and administrative infrastructure in this desperately poor, huge country.
Meanwhile, Khartoum finally admitted last week that it had been involved in bombing incidents in recent weeks, claiming they were an accident; a few more such incidents and the insecurity will be enough to deter many from making the effort to get to the polls.
It's a sign of how world geopolitics has dramatically changed that the role of the US in the situation has significantly declined since the banking crisis of 2008. Its relationship with Khartoum has never been good, China and South Africa are regarded as having far more influence with the north. Would they recognise an independent south Sudan? For China, such sovereignty issues are handled with extreme care for obvious internal reasons.
Already, there is recognition that an agreement will be urgently needed between north and south to decide first on the new border but also how to share oil revenues and how to determine citizenship rights including for the several million southerners who fled the war in the south.
Sudan has long been one of Africa's most tragic histories; it is approaching a crucial milestone. Despite the considerable international concern, for the southern Sudanese this vote represents a long-cherished hope of independence. The most hopeful observers argue that while some fighting may be unavoidable, it is not in the interests of either the north or the south elites to allow a return to all-out war, given the need to keep the oil revenues flowing into their patronage networks; that may offer a fragile basis for peace.
If you want to follow events in Sudan Peace Direct is sending out a weekly update in the run-up to the referendum - and it is also funding some remarkable conflict prevention projects in the border areas.