Thanks for your replies. I went to Jessops and explained (complained!) and they tried reprinting some of the shots to check whether it was a just a one-off glitch. The prints were just as bad (if not worse in some cases). So I got a refund.
I think Jessops really isn't the best place for me to get prints done as they're not knowledgable enough about colour spaces, ICC profiles and the like. They didn't seem to understand that the files I gave them included embedded colour profile information which would be useful (essential) for them to reproduce prints as I viewed them on my screen.
I'm sure that this has been covered before on these forums but can anybody recommend a good, knowledgable printing lab? Or redirect me to a thread on the topic.
I understand that I may have to convert my Jpegs to sRGB. I'm not a Photoshop wizz (yet). Is there a function within CS4 to convert a batch of Jpegs from one space to another?
Many thanks again for all the help given on this forum.