An extremely long shot I know, but worth a try... 
I loaned out my helmet at the weekend for a trip in Peak Cavern and it came back without the backup light. The route was a tour of the main peak streamway between Buxton Water sump and Far sump, with visits to Lake Passage and the muddy tube between Window Dig and Squaws Junction. On the way back out they also visited Treasury and the Treasury sump. Apparently the only significant bit of helmet-scraping-on-roof was diving through Lake sump, so it may be difficult to spot if it fell off in there!
The torch is a Fenix P2D. A traditional beer based reward is on offer for it's return!
I loaned out my helmet at the weekend for a trip in Peak Cavern and it came back without the backup light. The route was a tour of the main peak streamway between Buxton Water sump and Far sump, with visits to Lake Passage and the muddy tube between Window Dig and Squaws Junction. On the way back out they also visited Treasury and the Treasury sump. Apparently the only significant bit of helmet-scraping-on-roof was diving through Lake sump, so it may be difficult to spot if it fell off in there!
The torch is a Fenix P2D. A traditional beer based reward is on offer for it's return!
