I don't know it's provenance but if it's described as lighter than 'Nancy Hayward' and darker than 'Jessie Clark', and is clearly a Gigantea hybrid, it's probably right. I suspect that the earliest flowers in August/winter are more saturated in colour than the later ones. I haven't grown it but I have grown 'Jessie Clark' and its blooms faded quite quickly on the plant, so perhaps this is also what is showing up in the photos here.
The photo of 'Flying Colours' in the 2014 Mistydowns catalogue shows what could be described as a dark pink/cerise/light red flower and the photo in Peter Cox's book 'Australian Roses' is also a similar shade.