I agree with the above figures.
LGW command currently 5-7 years, LHR commands currently 8-9 years.
Plus a further 8 years of career constipation, (no Posting and Promotion movement! 'Churn'?) is pretty well how I came to the conclusion of 12-15 years for a first sniff of a command, for the next people to join. I just think it needs to be factored into their thinking. That's all. I take no pleasure in saying it!
These figures don't take into account any shrinkage in the World economy, and associated 'downsizing' of the airline.
I don't think my figures will be far off the mark!