Hmmn, just checked the website and it said that 250ml of The One milk is a healthy extra - although I definately saw sainsbury's 1% milk in a SW magazine for 300ml!
well 100mls is 2 syns, which would mean 300ml is a hex which is 50ml less the skimmed (which i hate, like drinking water) but 50ml more then normal semi.
Just had a quick peak on the British Nutrition Foundation website and semi skimmed is 1.7% compared to 0.1% for skimmed so The One is as near as dammit to half way between - makes sense that it would be 250ml semi, 300ml The One and 350ml skimmed to me, I'd go with it x (I'll be letting my Mom know )