A gripping account of the scientists and architects who changed the shape of sound in twentieth-century Britain. On a winter's night in 1951, shortly after Evensong, the interior of St Paul's Cathedral echoed with gunfire. This was no act of violence but a scientific demonstration of new techniques in acoustic measurement. It aimed to address a surprising question: could a building be a musical instrument? Pistols in St Paul's tells the fascinating story of the scientists, architects and musicians who set out to answer this question. Beginning at the turn of the century, their innovative experiments, which took place at sites ranging from Herbert Baker's Assembly Chamber in Delhi to Abbey Road Studios and a disused munitions factory near Perivale, would come to define the field of 'architectural acoustics'. They culminated in 1951 with the opening of the Royal Festival Hall the first building to be designed for musical tone. Deeply researched and richly illustrated, Pistols in St Paul's brings to light a scientific quest spanning half a century, one that demonstrates the power of international cooperation in the darkest of times.