The buds first appeared several weeks ago but only started to open 2 days ago..
Photos show the problem
What is the problem? It looks like maybe it could do with a drink but apart from that it looks ok.
Is it in a pot or in the ground?
If this is a first year rose, then I would restrict the number of buds to 3 or 4. B3 is correct saying that the plant needs more water, but you should let the plant establish itself for a year before allowing it to produce more than 3 or 4 buds/flowers. Firstly you want the growth to go into the roots, then once it has a firm root footing in the soil the flowers will be bigger and the plant will be stronger. I always add well rotted manure in early spring, this certainly boosts the plant and the amount of flowers produced. If you can't get manure, leaf mould or good compost and feeding will help the plant.
I have a climbing rose growing in a pot, it's well established, and is now a few years old. I water it well and feed in the spring then throughout the summer. There have always been plenty of buds which go on to flower well. Only thing that knocks back a half opened bud is rain and wind together! It used to be in the garden near honeysuckle and it did not thrive at all. So it was dug up and put in a pot! Thriving now. Also i put some cut off stems into pots of compost and they have rooted and shooted!
It's in the ground. It has been a dry spring in Kent but I've kept it well watered.
Not sure that my description of "first year" is correct - I bought it last April so does that mean it is now second year and if so does this affect the advice?
I would say that as it is obviously struggling to keep the flowers looking their best then removing some of the buds would possibly help the plant to produce less but healthier flowers. I am no rose expert, but that is what I would do, and see how well the remaining buds perform.
When you say well watered Grandad - I used to make the mistake of sprinkling a bit of water on my plants often, but now I give them a good soak - say twice a week depending on how dry the weather is, if they are in pots and feed regularly. In the ground I up the water when the plants start into new growth, so for roses that would have been late Feb or early March.