In the diagram below you can see two points in the Earth's orbit: on the left we see that the axis is tilted away from the Sun (in the Northen hemisphere), and on the right it tilts towards the sun, the angle of tilt being (at present) around 23.5°. Scotland lies at between 55°N and 60°N, approximately, shown by the dotted line.

The solstices, in the plane of the Earth's orbit (click for larger)

If we now look at the same two positions, but this time from way above the Sun's pole (and with the Earth's size even more exaggerated (and yes, I know that the Sun hasn't changed orientation, but there aren't too many pictures taken from way above the pole....)), we can see that the dotted path does not spend the same amount of time in and out of daylight (below).

The solstices seen from above (click for larger)

On the left, which is the Winter Solstice, the arc of daylight is at its shortest; on the right, at Midsummer, the day is at its longest. Winter Solstice tends to occur at around December 22nd/23rd (which will always be the case because we make sure that our calendar doesn't drift, by adding the occasional second to the year length, as necessary).

At the intermediate points in the orbit we have the Vernal and Autumnal Equinoxes, in which the day length is exactly half a solar day (give or take...), everywhere on the Earth.