FWIW the article does make sense, though the conclusion I'd draw wouldnt be the same as theirs but:

Jane is earning £60k and claiming child benefit for three children. That’s worth £3,094.

She’s now in the 42% tax band.6 Jane still pays basic rate tax for her income between £12,570 and £50,270, but now pays 42% tax for everything over that. So her total tax bill is (50270 – 12570) * 28% + (60000-50270) * 42% = £14,643 and Jane takes home £45,357.

Jane is thinking of working a few more hours to earn another £1,000. She’s in the higher tax band – so in a sane world she’d expect another £420 of tax, and a marginal rate of 42%.

But that is not the result. Once Jane’s income hits £60,200, the “High Income Child Benefit Charge” (introduced by George Osborne) starts to apply to claw back her child benefit – 1% for every £200 of earnings.

The marginal rate – the tax Jane is paying on that new £1,000. This is 56.5% – and we will have the same result for all incomes between £60k and £80k.

The solution I'd draw from that would be to raise the higher rate from 42 to 45-50% and scrap the means testing of child benefits. Makes the tax take more progressive and reduces administrative burden by not having to assess people's income for if they are eligible for child support or not.