Can you ID this flower?

Stupidly, I didn't take a picture, so I'll try and describe as best I can. I saw it at Alnwick gardens, so is anyone going there soon?
It looked a bit like a blue convolvulus, but the flowers were very small. The stem and leaves looked almost as if it was a bulbous plant, very soft and juicy looking.
Any thoughts?

 

Looking at pics of convolvulus, the flowers weren't so open as that either, but still bell shaped. Lovely sky blue.

 

It was in the ornamental garden, along the back wall. It didn't have a label and looked as though it might have sneaked in as there wasn't much of it.

 

Was it a Campanula? These come in many shapes and colours, but blues are the most common
http://images.google.co.uk/images?hl=en&ie=ISO-8859-1&q=small+campanula&gbv=1

 

I don't think so, although I'm no expert. I have a couple of campanulas and the buds on the mystery plant didn't seem the same and it just seemed much more fleshy.