It sounds like leaf gall Steragram which camellias can be prone to. You can buy a spray to prevent this.

Very difficult to say anything without a photo because you've already described a dozen or so possibilities.

Thats odd Paul because there were no photos at all in my diseases book that were remotely like it...

Thanks for the suggestion 3d - I hadn't heard of it. Have checked pics on google and pretty sure its not that though.
As its only two leaves I think I'll just take those off and keep my eyes open.

Yes that what I do Steragram as I get the mould and fully browning on the leaves so I just pull those off with the mould or scaly bugs I get my grandson to dig them out and I then can wash each leaf with a sponge scourer in washin up liquid if it covered most of the shrub.

Yes, washing the shrub is labour intensive but it works - and its your grandson's labour, which can't be bad! If you get the white fluffy scale (mealy bugs) you can paint them with meths and they die immediately without harming the leaves- easier than washing the whole shrub!

Thank you Steragram for the advise on the mealy bugs and meths.