The stereotypical American secular Jew would love the ideal of the Lib Dems. The reality of the Lib Dems and the difference between secular American Jews and British Jews would explain why the LD share was so much lower than I expected.
I would be interested in your views as to how you consider Jews of the two nationalities to be different. I have never thought about that before. Granted the Tories these days have a more secular - and less Christian-centric - image than the Pubs do these days, but you are suggesting it is less about the image of the parties, and more about the differences between the two groups of Jews themselves.