Rent/mortgage is dramatically less than that in Dubai; for what you're paying £3k/mth in Dubai you'd pay £1k/mth in South London. So even though FO to FO looks like a 50% pay cut on paper, the gap in disposable income quickly narrows after housing costs
Housing (mortgage) costs in nice, non-Selhurst Parky, areas of London haven't been that low in 7-10 years. Not unless you're after a small flat or have a huge deposit for the mortgage.