If you look at the tax and NI bills for people (under the age of 65) whose income is solely from working a job (i.e most people) then the following gives you an idea of how many days you have to work to pay off that annual bill:
So, for example, if someone earns a gross income of £20K they have to pay twice as much tax and work 13 days more than someone who earns £15K.
And although someone on £40K earns twice as much as someone on £20K they have to pay more than 3 times as much tax and they have to work an extra 19 days.
Also I don't know many people on £50K+ who work less than 10-12 hours per day so they are putting even more time than those doing 8 hours per day.
P.s. Knock one day off your total for each extra week of annual holiday you get. P.P.s Calculations don't include pension contributions or other allowances/deductions.