I'm sure that Edrington made clear, at the same time they did a packaging overhaul of HP a couple of years ago, that HP is caramel free. If you believe them that is, I know I do.
In fact from http://www.highlandpark.co.uk/whisky/core.asp:
All Highland Park is naturally coloured; the only control for consistency is the degree to which sherry oak is used. Colour is achieved by varying the element of refill casks, that is to say oak casks that have previously held whisky and which, by extension, give less colour and are less active than first fill casks. Consistency is also achieved by the practice of cask harmonisation prior to bottling.
I find HP12 to be the best (chill-filtered/40%) standard malt around these days. Always have a bottle on the go.
Apparently, Willie uses it for a mouth-wash/palate-cleanser.