Thanks,
On my current under desk PC it needed to be set up as left and right screen, and I had presumed that once the sp3 was set up that way it wouldn't cope when on the go without resetting.
At least with most modern versions of Windows, the display configuration will be remembered as you move from monitor to monitor. I have my Lenovo T420 configured to extend the display across its internal panel and an external 24" display via DisplayPort at one work location and a different 24" external monitor via DVI in a different location (both equipped with docking stations). The relative position settings are retained at each location.