-connect over ssh fails to communicate with vnc service

[WireFreeBloke]

I've got VNC installed as a service on XP Pro, and have OpenSSH for Windows
installed and working with VNC in loopbackonly mode. I can connect in using
a VNC client over an ssh tunnel, and can "add client" from the server tray
icon to connect back over an ssh tunnel to a listening client. That's all
fine.

What I wanted to do was connect in over ssh, and have "winvnc -connect
localhost" run as part of the login script, thereby establishing a
connection back to my listening client.

The winvnc process is started, and can be seen in the task list, but it
doesn't instruct the already running service to make the connection, it
seems to hang - I'm assuming because it's not running from a GUI console.

Any ideas?

Many thanks
Martin.