£5k take home in London/SE is not a King's ransom given sky-high house prices in that part of the UK.
I live north of London and work out of STN. In this beautiful, uncongested part of the country house prices are 30% lower and my £5.5k as a youthful 737 skipper is tolerable.
But I've always said you'd have to give me at least a £20k pay rise to encourage me south of the Thames. Take away my stable family-friendly 5/4 roster and I'd want at least £30k extra.
Horses for courses.