The bacteria which caused London’s Great Plague has been identified for the first time, with scientists hoping it can provide greater understanding about the spread of disease.Yersinia pestis, which is thought to be the cause of the Great Plague, was found in skeletons which were discovered last year in New Churchyard, east London, during a Crossrail dig. There was always debate around whether the great plague was actually ‘plague’- the discovery of this bacteria puts such controversy to rest.Dr Richard Stabler Plague, fire and war: for London, 1666 was truly an annus horribilis Dr Richard Stabler, associate professor at the London School of Tropical Medicine, said the confirmation of the bacteria put to rest previous misconceptions over the nature of the disease.He said: “There was always debate around whether the Great Plague was actually ‘plague’. The discovery of this bacteria puts such controversy to rest.”The plague of 1665-66 was the last major outbreak of bubonic plague in Britain and killed nearly a quarter of London’s population.The bacteria were traditionally thought to have persisted in rodents, which were blamed for the spread of the disease as hosts for fleas.Fortunately, the Plague bacterium that was extracted from the site does not survive in the ground. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. Bill of mortality for 1665 shows more than 68,000 deaths from the plague in London Dr Kirsten Bos, who led the DNA analysis at the Max Planck Institute and helped positively identify the bacteria, said: “We could clearly find preserved DNA signatures in the DNA extract we made from the pulp chamber and from that we were able to determine that Yersinia pestis was circulating in that individual at the time of death.“We don’t know why the Great Plague of London was the last major outbreak of plague in the UK and whether there were genetic differences in the past, those strains that were circulating in Europe to those circulating today; these are all things we’re trying to address by assembling more genetic information from ancient organisms.”Dr Bos and her team will now continue to sequence the full DNA genome of the bacteria to better understand the spread and evolution of the disease.