But heres a snippet from the net, and yes, mine are south facing, so they could have been frost damaged last winter.
"Camellias need shelter if they are to thrive. An area in dappled shade under trees is ideal, but they will tolerate a more open position if shaded for part of the day. A west-facing aspect is perfect as strong early morning sun on frosted flower buds can cause them to thaw too quickly and drop off. In very exposed gardens, camellias are best fan-trained on a west-facing wall."