London Metropolitan Archives Information Leaflet Number 41 explains the situation
Coroners’ records for London and Middlesex
https://www.cityoflondon.gov.uk/things-to-do/london-metropol...

"all the coroners' inquests and depositions for the County of London dating from after 1875 but before 1927 appear to have been destroyed. From 1927 to 1965 the records were weeded and for most years only a 10% sample of the inquests has been retained. An index to the surviving files can be consulted by staff on request."

John