Completely different subject. I didn't say anything about trickle-down. I would start with tax cuts for low to middle earners, say by raising the threshold for income tax to £20k or £25k, and/ or by cutting VAT.
The difficulty is making this revenue neutral - unless of course you're in favour of increasing the deficit.
Can you remember the 70s? There was a really big deal back then, with punitive tax rates (97%) driving the Brain Drain. One of the national papers had a headline "Last one out turn out the lights" or similar. Anyone with an education or who ran a business did their best to get out of the country. Unemployment was 2 million and rising.
Then again marginal tax rates were equally high in the 1960's when the economy was apparently going gangbusters and London was swinging. The Beatles even sang about it.
If Corbyn and his supporters want to revisit this experiment, they will ruin the country, again. Try recruiting doctors here if they have to pay 50% tax rates when abroad they might pay 25%. "Tax the rich" is easy to say (and they are taxed already anyway), and "tax cuts for the rich" is the cheapest of cheap shots to chuck around....and both slogans reveal economic illiteracy.
Which countries have marginal tax rates that low ?
Of course even if your marginal tax rate is higher, that may be more than offset by higher wages. 50% of £100k is more than 75% of £50k (ignoring the fact that both are marginal rates).