After a lot of reading regarding the latest version of WUA, have come to conclusion that Microsoft has made this a silent and forced update.
So regardless of what settings you use for updating Windows this update installs in the background.
There is no reference to this update when using the service and no redistributable standalone installers for it.
Information from Microsoft.
Improvements made to version 7.6.7600.256 of the Windows Update Agent
- Hardened Windows Update infrastructure so that the Windows Update client will only trust files signed by a new certificate that is used solely to protect updates to the Windows Update client.
- Strengthened the communication channel used by Windows Update Client to protect it in a similar way.
If you turn on the Update Services ... some software components ... will need to be updated from time to time. These updates must be performed before the service can check for, download, or install other updates. Update Services are "turned on" if you choose one of the following settings: (i) install updates automatically, (ii) download updates automatically and choose whether to install them, or (iii) receive notifications about updates and choose whether to download and install them. ... If you turn on the Update Services, regardless of which "turned on" setting you have chosen, required updates to some components of the service will be downloaded and installed automatically without further notice to you.
If you would prefer not to receive required updates, turn off the Update Services.