It's all changed post COVID.
I work in the City (insurance) and see less ties now, apart from on the old guard.
Smart trousers, shirt and shoes should do him fine.
Don't listen to "no brown in town" ...
I wear smart jeans and brown boots with a white shirt and look as well dressed as many others.
Some do still wear suit, shirt, tie and black brogues, so that'd also be fine, if a little unnecessary.
Good luck!
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