Camelia's.

I agree with Gally, Kitty - you've definitely done the right thing with the ericaceous compost, but perhaps it's got waterlogged.
Shrubs in pots need lots of stones at the bottom to allow drainage.
The other thing that Camellias are supposed to not like is sunshine in them first thing in the morning, but that may be a gardening myth.

I think they are a bit hit and miss. I have mine planted against a west facing wall so they get plenty of sun (dream on). The older one, a beautiful pink, is flowering profusely but sadly all the flowers are wind burnt; the younger smaller white one is in bud so I am hoping for the best. Hopefully someone more experienced in Camellias can give you more info. I don't think they like too much wet - which is difficult in this country!

I find my Camelia keeps me on my toes KittyF. Mine is in the border, but was planted in a large hole, and back filled with ericaceous. The cold winters a couple of years ago almost did for it. I'd wrapped it in garden fleece during the frost and snow, but the last two years any flower buds have dropped off before opening. The leaves were also curling. Last year, I fed it lots, and dug in ericaceous compost in spring and autumn. The leaves are no longer curling, and it has many more buds than for some years. Yesterday, several had opened, without falling off. Sorry, that isn't much help, but it does commiserate.