Found this is a known bug
Solution to get the client started is to run (as root):
service boinc-client start
Although this service is supposed to start automatically for runlevel 5 it did not seem to do this last time I booted. May be a transient, or I may have to manually start it each time. The service is listed in /etc/rc5.d as 'K02boinc-client'.
The 'K' stands for 'Kill' - I should have remembered that! Doh! Solution was 'sudo chkconfig boinc-client on'.
THEN, to get the manager to run, I have to run it as root, either via 'sudo boincmgr', or by logging in as root and running it directly.
Thank you linesmen, thank you ball-boys.