The road system in Zambia is extremely simple. There are only a few major roads, and Lusaka on the road map is defined simply as a crossroads from which spring the 'Great North Road', the 'Great East Road', the 'Kafue Road' heading southerly, and the 'Mumbwa Road' heading West. I've followed the Great North Road almost as far as it reaches, straight up into the Northern Province, and turned off to the NorthWest reaching the town of Kasama. From here the road deteriorates markedly and is badly potholed. The last 250 km takes one to a T-junction. 5 km to the right is the town of Mbala. 25 km to the left however is my destination. Following this, the road drops quite swiftly through a thousand metres as you drop into the Rift Valley. Surrounded by the heights of the Zambian plateau is Lake Tanganyika. My road lies parallel to the valley and the lake and meets the shores at a small dusty down called Mpulungu, generally pronounced 'poolungoo', and we're 1140 km North of Lusaka at Zambia's only port.

Polonium has no biological role and any sample used to kill the former KGB spy must have come from either a research laboratory or nuclear facility. It is found in uranium ores but at miniscule levels 0.00000001%. So small that the Curie's were awarded the Nobel prize for their superhuman effort to extract it. Could a terrorist smuggle Polonium into this country or is there a human leak at a UK Defence Establishment? Gramme quantities of polonium-210 are synthesized from bismuth in nuclear reactors. Carrying quantities of polonium is difficult because of the high temperature from radioactive decay [500oC] and the emission of deadly alpha particles. These radioactive particles are most dangerous when ingested. They pick up electrons from cells in the body and escape as helium gas. Polonium-210 has a relatively short half life [138 days] so the 'evidence' diminishes constantly with time. Also Polonium is fairly volatile and will evaporate if not kept in a sealed container. Polonium is one of the deadliest known substances and is believed to be a trillion more times toxic than HCN weight for weight.