[ubuntu] Font sizes after upgrading to 16.04

I've just upgraded my main Ubuntu install from 15.10 to 16.04 using a method that I've never used before, that is upgrading using an ISO rather than via the update manager.

Everything seems to have worked well and after adding the various PPAs that were deleted in the upgrade process I'm back to using Ubuntu but with one very significant difference. In some applications such as Google Chrome, gnome-terminal and terminator the font sizes seem to be much smaller than what what I was seeing before the upgrade. In other applications I'm not seeing any change.

Is this a bug, just my imagination or have there been recent changes that I'm unaware of that would explain what I'm now seeing.?