In article o.uk,
Dave Liquorice wrote:

The bearing will be correct no matter the time of year

That's not true, unless you read the time from a sundial rather than a
mechanical clock. The eccentricity of the earth's orbit and the fact
that the sun does not stay exactly within the plane of the equator mean
that sun time varies from human time by up to 16 minutes, which
corresponds to an error in the bearing of up to 4 degrees.

See http://www.sundials.co.uk/equation.htm

-- Richard