Yesterday I was on a Boat called Wind K, it's a boat speciallized in arranging trips for the Thistlegorm everyday, I witnessed this situation: a Russian guy (early 50's IDC staff), his wife (late 30's Rescue diver), and his daughter (not more than 13 years old Jr. advanced open water) ..
- he decided to take them down to the Thistlegorm,
- the main guide of the boat refused,
- the Russian guy said ok, i take her on my resposibility
- the main guide guide stuck to his decision, and told the Russian guy: "if u insist taking the girl down we will check her depth gauge, and it MUST not exceed 21m., otherwise we will report ur Diving Organization"
- it ended up, and the girl didn't dive at all.
i think the main guide of the boat was right, regardless how experienced the little girl was, she can't afford such a dive.