How do I get the default Network Manager plus dnsmasq-base setup back again?

[Chris Green]

A while ago I installed the 'full' dnsmasq package on my desktop machine
so that it ran as a the DNS and DHCP server on my LAN.  In addition to
installing dnsmasq (and configuring /etc/dnsmasq.conf) I commented out
the dns=dnsmasq line in /etc/NetworkManager/NetworkManager.conf.

This setup worked fine for a while but now I want to use another server
on my LAN to provide DNS and DHCP.

I have removed the dnsmasq package from my desktop machine and have
uncommented the dns=dnsmasq line in /etc/NetworkManager/NetworkManager.conf.
However Network Manager *isn't* running dnsmasq as it should.

How do I get back to the default setup with dnsmasq being run by Network
manager as a caching DNS server?  I have tried uninstalling and
reinstalling Network Manager but that doesn't help at all.

What do I have to do?

-- 
Chris Green