If any of them live in London (and they surely do) then I'm not surprised. Renting (or buying) a modest 3 bed (say 1000 sq feet) terraced home inside an hours

If any of them live in London (and they surely do) then I'm not surprised. Renting (or buying) a modest 3 bed (say 1000 sq feet) terraced home inside an hours commute of central London will easily eat 50% of what you take home out of a £100K salary. Factor in the incredible cost of child care (meaning it's barely worth your partner working unless they're also in a highly paid career), saving for retirement, and the steadily increasing cost of living (fuel, food, energy) and raising kids, and you're not really leading a life of luxury or building any wealth.