In the middle of replacing all the superb bulbs with LEDs but can't quite release the panel. I've taken the panel over the alarm sensors out and the two screws and it's hanging down now but just won't come out. Anyone know what's at the front?

I believe you can just take out the cover “glass”. No need to take it all apart. 
Use some some flat tool to pop it off, it has few small clips. 

Thanks Luei, I did try that but it was a bit reluctant to budge. I noticed that the previous owner changed the rear bulbs but not the front and I can see why now as that took two mins. 

Got it now. Just had to a bit firmer. Thanks Luei.