Not necessarily. When a Camellia is short of iron, its the leaves which reflect that, not so much the flowers - the leaves will look yellowish and sometimes mottled yellow. I'd like to know if this plant gets early morning sun, that is, the sun hits it as soon as it rises - any dew or frost on the flowers and buds, once the sun hits it, will cause browning of both.

Thank you so much for this, it's very helpful. The area gets afternoon sun mostly and nothing first thing in the morning? Any suggestions on how I deal with the dew or frost situation daily without having to cover the plant every day?

Ah, well if it doesn't get early morning sun, its not a problem, frost or dew, sun on frost won't be the cause of the browning.
You haven't said where you are in the UK - drought could be an issue for yellowing of flowers - dryness at the roots might cause this.
Alternatively excessive rain can cause balling and browning in some Camellia varieties. I have to say I got rid of all my Camellias because of this browning problem - the only one I now plant is red flowered varieties, because they seem to suffer much less with flower problems.
By the way, if you have bought the Sequestrene, use it - see if it makes a difference. It certainly won't cause the plant any harm.

I'm in Richmond, Surrey. Camellias seem to be a real problem I agree as pretty as they are! And mine is right in front of the house. I'm going to use the Sequestrene I think, then use your advise by trying to water a bit more. If that doesn't help I'll assume it's too much water! Thanks very much for your help and advise.

Given where you are living I would think it is lack of water rather than too much.

Thanks both. I'm going to assume that I'm not giving it enough water.

Remember Marifirbank,rainwater is best I think

If you've got any rainwater to use! Otherwise fill a bucket with tap water and let it stand for at least 48 hours.

Water with boiled and cooled water if no rainwater available, but I wouldn't worry too much, tap will be fine, specially if you use the sequestrene. Remember you can't use your hosepipe from Thursday though...

I think cold tea is also suitable for watering camellias as it is slightly acid

Good point Andrew - though we drink all the tea in our teapot!

We dont have any restrictions on water with Severn Trent.......yet.

They will in Richmond, though, that's not far from me... tomorrow's the last day you're allowed to use a hosepipe.

And Yorkshire Water is warning that some areas are entering drought conditions!

Just taking a break from mulching - got everywhere nice and damp, now I'm spreading 2-4 inches mulch everywhere to stave off the plants dying of thirst... makes your back ache, all that shovelling and spreading.

Thanks all for the ideas! I've done the sequestrene so let's see how it goes. This is its last chance however, otherwise it's out and making room for something a bit more hardy! Oh the hose pipe ban ..... how will we manage!

Use a watering can nothing else for it.