Hi thereI was pleased when I saw there were many buds on the young Clematis I planted last year

did you have a frost last night? If they haven't perked up during the day then this might be clematis wilt.
link to the RHS site. where it gives you he current advice.
https://www.rhs.org.uk/advice/profile?PID=125

Wilt is not as common as people think. Also it starts at the bottom of the plant and works upwards, so if it is the top of the plant which is wilting then it is not Clematis wilt. I would check that the stems have not been chewed by snails down at the base. they love to strip the bark from the stems and then of course that stem dies (from the top down through lack of water).
Agree if you had frost overnight that could have an effect on the buds too.
Is it in a pot or in the ground. Pot grown Clematis can be attacked by vine weevil grubs, but then the whole plant wilts rather than just the flower buds.
It could just be drought, Growing Clems need an awful lot of water.
A picture might help.

I just typed out my thanks and comments, but they haven't shown up on this page, so at the risk of duplicating I will start again.

Yes, we have had several nights of frost, but the foliage remains green with no blackened tips. Photograph above. On looking closer this morning, I see that not ALL the buds are wilting, but around 25% are. No frost last night, but the buds sadly haven't perked up, so far. . :-(

No traces of snail/slugs. The plant lives in a container and I am careful not to let this dry out. I will also now protect for vine weevil.

Thank you once more, hope this second message shows up

yes your message has shown up this time. Pots do dry out faster than we imagine especially as it has been breezy of late. Give it more water than you would usually especially as it gets bigger.