What we thought we knew is wrong. The Black Death arrived in Britain from central Asia in the autumn of 1348 and by late spring the following year it had killed six out of every 10 people in London. Such a rate of destruction would kill five million now. Researchers extracted plague DNA from 14th century skulls found in east London and evidence suggests a different cause: only an airborne infection could have spread so fast and killed so quickly. A pneumonic rather than a bubonic plague.