I am not sure why that one specific plant does but camellia bud drop is common for a variety of reasons:

* large fluctuations in temperature and-or moisture can cause bud drop so try to provide evenly moist soil with no periods of dry-wet-dry-etc.

* varieties that bloom late in Spring can suffer from weather issues that make temperatures go up and down a lot.

* make sure that the soil does not lack nutrients, is poor and does not drain well.

* protect from camellia bud mites, which cause flower buds to develop slowly and either open late or fall off before they open.

* in some rare cases where none of the above explains/corrects the problem, there may be a problem with that particular variety or even that particular plant. Sweet Emily Kate does not have any reported issues like bud drop.

Thank you Luis. It produces a massive amount of buds, far more than any other camellia I have, or have ever had. I'll make sure I keep the water up to it, and that I fertilise it regularly. I hadn't heard of camellia bud mites, but it doesn't to appear to have any of those.

It's still Winter here (Sydney), but we have had a lot more temperature fluctuations than we normally do.