So... perhaps this is partially OT, but: according to a couple sources [1,2], income tax at £50k/year is just 17-18%, and National Insurance another 9%. This makes the total "tax bracket" around 27%. Even if the author means that 50k is his net salary, the same sources put the tax bracket at just 32% [3]. Why does the author say his tax bracket is around 40%? Are those sources unreliable? Are they missing some of the taxes?
[1]: http://www.netsalarycalculator.co.uk/50000-after-tax/