Bonuses

I wonder if the government will break the contracts of those who work for the banks who have bonuses built into their contracts.

The reason why banks pay bonuses rather than higher salaries is because the bonuses are not part of the employees pension benefit. They can transfer their bonuses into their pension funds and get tax relief. This is what many do, why pay tax when you you can receive it as deferred salary when you get your pension, on which national insurance is not paid.