Delia's tablespoon

Hi Lindsay,
I came across your explanations of spoon measurements, and it explained why I've had some not quite successful attempts at some of Delia's recipes.
In Canada, we use 1 tsp (5 ml), dessertspoon (10 ml) and tablespoon (15 ml). Now I know that Delia's recipes use a 20 ml tablespoon, I'm sure I'll do better from now on.
Is a 20 ml tablespoon a standard used in Britain? I'm wondering if I should be using that size for all British recipes.
Thanks.