This beer has now been bottled and is sitting in a warm cupboard carbing up. Keeping on with my trials, two 330ml bottles received 3mL's of espresso and some other bottles were carbed with demerara sugar.
100% Cane sugar (control)
75% Cane sugar, 25% Demerara sugar
50% Cane sugar, 50% Demerara sugar
25% Cane sugar, 75% Demerara sugar
100% Demerara sugar
Should have results back from the trials in four to five weeks.