Well if you like. At that time, thanks to Harold Wilson, the "taxman" was taking 95% of earnings under a "supertax".
When the highest bracket of income tax was dropped to 40%, it raised more tax money than the punitive 95% taxation had ever done.
The Beatles were warned that "two of you are close to being bankrupt and the other two could soon be"
One of the nice things about earning lots of money is that you just get a good accountant and move your domicile to Monaco or similar. The highest bracket of tax only ever squeezes money out of the sector of the population who are earning well, but not that well. By lowering the top rate, the multimillionaires, pop stars, etc were less likely to move their earnings off shore to a tax haven.