[ubuntu] No wifi after 16.04 upgrade

Hi all,
Have just completed the upgrade to 16.04 and have no wifi.
In the networking tab of the settings menu the is no option to enable wifi.
After some googling I saw a thread about lshw -C which gives me the following result

-network UNCLAIMED
description: Network controller
product: BCM43142 802.11b/g/n
vendor: Broadcom Corporation
physical id: 0
bus info: pci@0000:02:00.0
version: 01
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress cap_list
configuration: latency=0
resources: memory:b0500000-b0507fff

Within the Additional drivers tab of the update menu it show that it is using a proiprietary Linux Broadcom driver which is selected

Other than that I am stuck.
Have tried googling Network unclaimed but can only find old results, nothing relevant.
Any help very gratefully received.
Many thanks
Jon