@laughinghan if you have to ask my suspicion is that no word of mouth will be enough for you, so instead may I recommend:

http://en.wikipedia.org/wiki/Ross_J._Anderson http://en.wikipedia.org/wiki/Markus_Kuhn http://en.wikipedia.org/wiki/Steven_Murdoch

...and http://www.lightbluetouchpaper.org/ ; I am unaffiliated with Cambridge other than knowing a few of the people there.