Oh no, it isn't.
The tax that dare not speak its name is employer's National Insurance, which would be around £93.37. It's an extra cost that the employee never sees, but it's money that could be paid in wages if it were not deducted at source. Therefore, the gross (pre all stoppages) pay is higher than shown, and so are the deductions.
So why don't we see payslips that tell the whole story, say something like this? ...
The reason is obvious, isn't it? Especially when you show the appropriate marginal rate.
And if this was a payslip for someone not in an occupational pension, the marginal rate of N.I. would be 11% for the employee, and 12.8% for the employer. In other words, £100 extra payslip-declared salary would actually cost the employer a total of £112.80, with marginal-rate deductions of £22 in income tax and £23.80 in N.I. ! In that case, the real effective marginal rate of revenue-raising would be 45.80/112.80, or 40.6%.
The average wage earner is, in fact, a 40% taxpayer, without knowing it.
Is it illegal to show the truth on your employees' wage slips? Don't you think it would make the ordinary person start to take the taxation issue seriously?