I did not see your original question, but have checked back and looked at what you said, and at the answers.
One other thing to check - examine the backs of the leaves and the stems and branches. You're looking for small, shield shaped objects which don't really want to come off without your scraping with a fingernail. If you find those, then your Camellia has scale infestation. If its on the stems, you can use a cloth lightly moistened with methylated spirits and rub that over to remove the blighters. If its on the leaves, you can't, you'd need to buy the Provado treatment which treats for scale. Scale insect also causes sooty mould on the leaves, which you can treat by washing gently with horticultural soap and water.

Thank you for your input. I looked under leaves and only found tiny yellow/green things which I,m presuming are aphids as I could wipe them off with my fingers.

Camellia scale are 2.5mm long, yellowish light brown to dark brown, so about the same size as aphids. Google Camellia scale, you should find pictures of it present on leaves - just in case!