[Peter Cornwell]

As at 18.00 hours on 20 August 1940 there were 610 Hurricanes fully serviceable in fighter squadrons with another 48 serviceable within 12 hours. Similarly, there were 322 Spitfires fully serviceable with another 19 serviceable in 12 hours.

In addition, 40 Hurricanes were fully serviceable at No.5 OTU with another 23 serviceable within 12 hours, while No.7 OTU reported 58 Spitfires fully serviceable, with another 35 being so in 12 hours.

Source: 'State of Aircraft in Fighter Command' an original Equipment Branch document in my collection.