In 4/5 years, my virginia creeper, growing on a south-facing fence in clayey soil, has never coloured up in autumn. Some leaves sometimes go anaemic pink before dropping.
Moving back up the forum so maybe someone can help.
Just saw this. Not sure of the reason Rosemary. Where I work there is Boston Ivy (same family) growing on the south facing well and it colours beautifully. Perhaps it is the soil although we're on clay here too. Is there any other planting round about and how does it look? Perhaps a feed or something may be required although usually these creepers don't need much assistance.
Sorry - I'm not sure that was much help
Rosemary, would it be possible for you to upload a photo of the plant? There is a possibility that it's not a Parthenocissus quinquefolia. Does your plant get berries?