Dean, that last line is interesting. I used to struggle to hit higher paces in training.
What might be good for that, as well as working a different fitness zone, is for you to move one of those hard sessions to incorporate Marathon pace (MP).
Sub 1hr 30 is 6.52 pace. We work to your current fitness, so call it 6.55, and thus your MP would become around 7.20.
The session would eventually become 3miles warm up, 5-6miles at MP, 1/2mile cool down.
You might need to build from 2-3miles MP to start with, but over a few weeks, you'd handle the full 5-6.
You'd then make your other hard session, specific to the aim.
If half marathons are kicking in soon after, I'd perhaps do something like
3 x 2miles at HMP, off 2min recoveries.
This way you have the classic tempo and intervals added in your schedule.