Plague of 1348-49 spread so fast in London the carriers had to be humans not black rats, says archaeologist. 

Rats weren't the carriers of the plague after all. A study by an archaeologist looking at the ravages of the Black Death in London, in late 1348 and 1349, has exonerated the most famous animal villains in history. 

Sloane, who was previously a field archaeologist with the Museum of London, working on many medieval sites, is now attached to English Heritage. He has concluded that the spread of the 1348-49 plague, the worst to hit the capital, was far faster, with an impact far worse than had been estimated previously.

While some suggest that half the city's population of 60,000 died, he believes it could have been as high as two-thirds. Years later, in 1357, merchants were trying to get their tax bill cut on the grounds that a third of all property in the city was lying empty.

Sloane spent nearly 10 years researching his book, poring over records and excavation reports. Many records have gone missing, while there was also a documentation shortfall as disaster overwhelmed the city. Names of those buried in three emergency cemeteries seem not to have been recorded.

However, Sloane found a valuable resource in records from the Court of Hustings, of wills made and then enacted during the plague years. As the disease gripped – in October 1348 rather than the late summer others suggested, reaching its height in April 1349 – the numbers of wills soared as panic-striken....