Mugabellew was on the flightdeck of my flight to STN - and we asked him about the hours issue. He said that he was driving the "optimiser" software to get all pilots - Ryanair and contract - within 5% of each other - when annual leave was factored per month.
I did not understand how he could do this but he said that he had a statistician working weekly producing reports by base by rank and employer. Each base was then manually adjusted on the roster and inspected to ensure that all pilots would converge. I asked how could this work with more than 2500 pilots.
He booted up his laptop (non SOP on the flightdeck I know) and showed both of us the live data. Uncanny the lowest and highest in STN were within 6%. He said to drive this on that in some bases it means that some will have markedly more flying than others to bring them into the statistical band.
He referred me to a book called "fooled by randomness" and claimed that airline flights operations and rostering were the ultimate wonder of game theory. As he tried to explain a "polar aerograph" to me displaying hours by base - I pretended to have an RT call to make.