There are other opinions indicating that CloD modelled the
- the Magnetic Declination of the Dover channel in 1939-42 = -8°
- the Deviation, aircraft magnetic interference = varies from aircraft type and aircraft heading, usually a table with heading
- course drift from wind
Bristol Blenheim flight from London to Dover, 115°T, wind 230°@5m/s, Blenheim Deviation at 115°T = -1°
Which compass course to fly?