Got to the running track tonight to find that the floodlights were off and park closed
so over the fence I went anyway ... 
Only problem with running in the dark is that I could not use the backlight on my sportswatch to monitor my pace as I had set my watch to manual laps to capture the 800m intervals and tapping the watch for the backlight activated the manual lap time so I had to run blind.
Did 7 and a bit laps as a warm up at 9:52 mm pace, followed by :
Interval 1 (800m) 3:09 mins
Interval 2 (800m) 3:12 mins
Interval 3 (800m) 3:15 mins
Interval 4 (800m) 3:12 mins
These times equate to an average of 6:30 - 6:35 min/mile which is much quicker than I thought I could do.
I walked / jogged 400m in between each interval and finished off with about 4 laps to cool down in 9:549 mm pace.
The 400m recovery laps got a bit longer each time and certainly by interval 3 I knew I was pushing it but decided that I might as well finish strong.
I cannot say that I enjoyed it but did feel good afterwards when I realised how fast I went and how consistent I was too.
I need to think about how I build on from here. Should I repeat the 4 reps next week and then move to 5 reps the week after ?