I found a solution! extra pleased I must say.
I found that although I had whitelisted module "wl" it did not appear in lsmod output, and when I tried to modprobe wl I got modprobe: FATAL: Module wl not found.
Here I must divulge that I got inspiration for this inquiry from an answer on askubuntu.com ( http://askubuntu.com/questions/459654/d ... rusty-tahr
I then checked out Rigo searching for Broadcom. I found that the Broadcom driver package for Kernel 3.14(Broadcom Sta 22.214.171.124-r1#3.14.0-sabayon) was not installed - this was a vanilla 14.08 installation.
3.14 is indeed the last kernel to have Broadcom wifi support
I installed the broadcom package, typed modprobe wl and, great relief and joy, my wifi works.
Must confess also, the child in me still gets a kick out of typing in a tiny command and then, hey presto, the machine works!