Working on vs life-span
"Anyway, having joined BA at age 40, my final pension at 65 under either scheme looks like it's going to be more than double what it would have been at 55 and I'll still be working in a decent job for that extra ten years too."
I hope you have factored in the fact that you will undoubtedly have a shorter life-span if you work those extar 8-10 yrs?