When we view Darby Corner roundabout from above, we realise it is not round. It has sections which are straight followed by 90 degree bends (some call this a squareabout). 

When we use roundabouts with straight sections, we need plan our exit sooner than a 'normal' circular roundabout.

If we don't, we may not be able to move over to exit and 'get stuck' on the inside lane, forcing us to go around again.

It is worth noting that this roundabout has no lane markings, there is room for two cars side-by-side, so it's important we either position to the left (using the outside kerbs or green hatch markings as a guide) or to the right (using the inner kerb as a guide).

In the following example, we are entering the roundabout from Canford Heath Road and want to take the third exit onto Gravel Hill.

Take note that we need to reposition early on the straight section before the exit before gravel hill.

If we do this, we will be perfectly in line with the exit.

It may feel a little odd signalling right, but re-positioning left!