LJ, huge thanks for your post, not nosey at all - i'm grateful that you went out of your way to have a look!
the 2x 5:30/mi was supposed to be 4x 5:30/mi but I just felt awful so cut it short - the same pace in the 1/2mara 1st mile was purely by accident

on reflection I think it was closer to 5:40, but still much faster than I'd have liked.
I think the thing is that when I'm running a mile repeat at say 6:20, I know I could run it faster, so I tend to... in light of your post though I think it'd definately be more worth my while training at race pace, and if I do 1mile intervals, work on increasing the number of reps over time. Speed endurance is definately what I lack!!!