Maybe she did see lights in the forest before 1980. One of the 'explanations' for the lights in the forest is that certain members of the base staff were addicted to playing practical jokes. Kevin Conde stated to the BBC that he was one of the hoaxers, shining different coloured lights from his security vehicle.
http://www.bbc.co.uk/insideout/east/series3/rendlesham_ufos.shtml
However his story does not seem to fit with the main event at Christmas 1980, since he gets many details of time and place wrong- this may mean that he was not involved at that time, but he may have carried out similar hoaxes both earlier and later, and this might have been the cause of some of the lights seen by Butler.
I'd guess that the light at Orford may have been responsible for at least some of the other phenomena Butler has seen- the light is apparently switched off now, and maybe that will reduce the incidence of strange sightings there. Alternately, I suppose, it might make it easier to see the real lights, especially if they have a supernatural origin.