Assume every tax rate except for the “personal allowance” was increased by 1% to fund free train travel.

Would you be in favour of this?

I've not done the math for this (though did look up some stats for a Scotland specific post, and it seems to be feasible: https://discuss.tchncs.de/post/44818305). So for the UK it may require a lower or higher increase (and to be fair my Scotland "calculations" were very rough and likely entirely wrong). This is more just a question about whether people would be in favour of something like this in general.