Both official campaigns received initial grants from the Electoral Commission, which is a publicly-funded body.
The NO campaign splashed a label on the front of their leaflet claiming:
None of your taxes have been used to print this leaflet
The implication, of course, is that the naughty YES campaign has been craftily using tax money! Perhaps the NO campaign used only donations to fund their printing costs, but this label is trying to trick voters into thinking that one campaign is doing something wrong.