Hi again
I still don't know the answer but what I've discovered through trial & error is this.
If I turn the bathroom sink tap on with a strong flow and wait a few seconds until it settles the water is cool enough to be able to use it. The stronger the flow the cooler the water becomes, the weaker the flow the hotter the water is.
My kitchen sink is right beside the boiler so even with a strong flow this is always pretty scalding unfortunately
Pat R
February 2010