So I ultimately sent Qantas a complaint because this page
Eligibility and Access to The Qantas Club Lounges | Qantas of the Qantas website states, under the sub-heading 'Families': "
Qantas Lounges welcome you when travelling together with your family. In addition to your normal guest allowance you may also bring up to two children, between ages 4 and 17, into lounges operated by Qantas"; and under the sub-heading 'BA and oneworld Lounges': "
This is with the exception of the oneworld Los Angeles Tom Bradley Lounge where Qantas Club members may be accompanied by two children up to 18 years of age in addition to their counted guests".
I received a reply by telephone explaining to me that "it is up to the discretion of the counter staff on the day to determine who will be allowed entry to the lounge". In other words, don't trust what we say on our website because we reserve the right to disregard this completely, even if the lounge is deserted as the Qantas First lounge in Hong Kong was when we visited.
Why bother even putting guidelines on the website when all they serve to do is mislead people about their lounge access rights?