VPN Passwords won't save in XFCE

In order to stop XFCE network manager dropping your saved VPN passwords, open the config files found in /etc/Network Manager/system-connections/, choose your preferred connection, and open in leafpad with:

gksu leafpad  [filename]

Add the following line:

[vpn-secrets]
password=xxxxxxxx

Where xxxxxxxx is your VPN password. Save file.