It looks like those clusters are just going over. Pelargoniums revel in warm, dry weather, because it reminds them of the blooming season in their South African homeland. On the other hand, it causes the flowers to age out much more quickly, especially if you are a bit late with the hosepipe.

Cut off the spent flowers & it will send up new ones.

Tug...how you mean"a bit late with the hosepipe"Theu are geraniums,never heard them called Pelargoniums before,BTW,I am from South Africa.
Bath,I have been cutting the spent flowers off,just wondered why they were going brown or if I were over watering.
Thank You both for replying to my question.

No criticism intended, Solada! I've been hearing about the hot--of course, I have a different perspective on "hot"--dry weather you folks in the UK have been experiencing. It would be easy to miss the need for extra water until the plants wilt, and plants never wilt without suffering some degree of damage. Even without accidental underwatering, very warm weather causes all of the plant's processes to accelerate, including flower fading. The picture doesn't show many leaves, but I am not seeing any of the kind of yellowing that overwatering would cause.

White flowers are more prone to sun scorch.

Solada, bedding geraniums as you have grown are members of the geranium family but the actual species is Pelargonium. Most people just call them geraniums. I suspect the heat is the main cause for the flowers to die off. white flowers often go brown when they die. just clip them off and the plant will send up fresh flowers.
also avoid watering then from the top as that can also cause browing. [ has your area had rain recently?]

And when you do deadhead, pull the whole stalk off from the main plant.

Thank you so much for replies.