I can top that one. It was a miserable misty November morning at our gliding club. I was on my second or third turn as duty assistant instructor. There was a batch of ab-initios hanging about hoping to fly.
Word came that the duty instructor was ill and could I take command till someone else could take over. I looked the sky and decided that flying might be possible but being a cautious type I felt that a weather check might be a good idea, so we got the winch positioned, a two seater D.I.'d, and cable laid. I called for a volunteer and a pupil joined me in the cockpit of our Capstan. At the time I thought what we had was just some mist, and that the cloud was higher. At 800ft (just like you) we shot into the cloud. By the time I realised that this wasn't mist, we were passing 1000ft. Too high to land ahead and maybe even S-turn, as ours was a very small field surrounded by suburbia on three sides. I decided to go to the top of the launch to give me more time to sort out this mess. At 1200ft we dropped the wire, right in the mirk by now. The only thing I could think of was to try to fly racetracks till we broke clear. The pupil had a good watch, so I briefed him to call out at every minute as the second hand passed zero and we flew S/L for one minute, Rate 1 turn on the T/S one minute, S/L again, turn, and so on till we completed two rounds of this, me battling to keep the speed as accurately as I could. We popped out at 700ft, and my guardian angel was with me, as we were just downwind of the field facing into wind. Full brake and a bit of sideslip, and we were back on the ground. I let the pupil do the landing as he needed the practice. We put the kit away and adjourned to our local as there was no further flying that day. No one ever mentioned this affair afterwards either. I learned about flying from that.
I ought to mention that I had done quite a bit of cloud flying in my Olympia which had an artificial horizon installed , so it was by no means a new experience, but I was lucky and I knew it. Very character building.