Bone Yard Oct Contest

Todays contest will be a Brain Teaser. I hope you enjoy it. You may only post 1 answer. Any extra answers will not be counted.

Teaser value: 1 point

I was having trouble sleeping last night and I tossed and turned well into the night. Our local town hall has a clock which strikes on the hour and also strikes just once on the half hour. During one of my more awake moments I heard the clock strike once, but I could not tell what time it was. Half an hour later it struck once again, but I still could not tell what time it was. Finally, half an hour later it struck once again and I knew what the time was. What time was it?

Ok, first one to post the correct time gets it.