Crammed into a quaint house in north London is one of the largest private archives of newspaper and magazine clippings from the past two centuries. Edda Tasiemka, an eighty-two-year-old native of Hamburg, Germany, built and oversees the ever-growing collection. Tasiemka, who fields dozens of calls a week from writers seeking background material, has been likened to a human Google. But she has a unique filing system, and, in some ways, a deeper memory.

On one recent Monday, twenty requests came in. One was about the fallen pop duo Milli Vanilli; another was for the British broadcaster John Humphrys. She charges anywhere from about $64 to...