Go on UK concentrates their work on 'potential users' and 'narrow users' as they classify them.
An interesting point for me is the fact that they call a group of 3-3.5 million people "active resistors". In my research in statistics for numbers of Non-Internet users I found that there is a group of resisting internet users, but it wasn't as large as this. The Oxford Internet surveys with their 2011 report differentiated between ex-internet users (people who used to use a computer) and non-Internet users. With this not to be forgotten the group of proxi-users; people who don't use the computer themselves, but get their son / daughter / carer or grandchild to do it for them. Are they active resistors, or simply comfortable with the set-up their have? In the OXIS report 80% of the ex-users and 60% of the non-Internet users indicated that they have someone they know if they needed to go online. In my calculations at the time (in Jan 2012) I concluded that less than 2 millions people are really digitally disconnected.
Link to Go on UK Link to Oxford Internet Surveys
