My phone can also be used for astronavigation. It has the Solun' planitarium software, which can display the azimuth of the Sun or Moon. The azimuth is just the bearing from north, so if the Moon is at 270 then it is due west. Of course if you can see the pole star than you don't need the Moon for navigation, but the UK is often too overcast for stars. And with the sun, it'll be more accurate than the "point the hourhand at the sun" method, especially if you don't have an analogue watch.

You can get the same information from some GPS units, and so get a rough bearing even if there is no signal. Mine has a screen which shows the relative positions of Sun and Moon on a compass rose. For example, stick a twig vertically into the ground so it casts a shadow. Switch the gps to Sun & Moon screen, and place it flat so that the shadow falls onto the screen. Rotate until the shadow falls on the line connecting the Sun and the Earth. Then the compass rose is correctly aligned and north means north.