Longshore Drift from south to north at Silloth

In Clarence Ellis's book The Pebbles on the Beach he says that longshore drift moves material from south to north on the west coast due to the wind-driven waves coming predominantly from the south west across the Atlantic and then up into the Irish Sea. The exception is apparently the stretch of coastline in Cumbria from Walney to St Bees where the movement is north to south. The photograph shows a view looking west at Silloth. Notice that the pebbles have piled up much higher on the left of the groyne. That means that material is moving from south to north as predicted.