Really interesting discussion and lots of well argued views.
Thing is.... we're all public transport advocates on this forum (or at least, most of us are). The idea that 1p on fuel duty... I think that might happen but not ringfenced for public transport. As a nation, we have crumbling infrastructure (roads, schools, hospitals), an increasing requirement for social care, pressures on public sector pay etc.
In short, there's a list of more publicly acceptable or popular recipients than public transport, and the Treasury will always fight against hypothecation (ringfencing) in any case, so 1p on fuel duty to pay for a continued bus cap seems unlikely IMHO. As I say, we are public transport fans and so we will naturally think that it's a fair and reasonable thing to do to increase taxation for the benefits that it can bring. However, we have to remember that most people will say they want better public transport...until the point that it results in increased taxation or they can't park their car outside their house or has some other adverse impact on their lives.
Anecdotally, I know of a few people who will occasionally get the bus now instead of the car. Part of the reason is the lower cost bus fare. This is backed up (I know
@GusB asks for evidence) in the latest Transport Focus report
However, we must also recognise that there is a difference between cost and value. All too often, we focus on the cost - at £2 to go into my local major conurbation, you'd wonder why more people aren't taking advantage of this? That's because we have growing traffic congestion and limited bus priority. It's important as people put value on time and a cheaper bus fare isn't the main issue.
It's a really difficult balance to strike and I'd like to see more innovative areas of tax policy. Give firms the incentive to provide travel passes and not be taxed as a benefit in kind? Or make it easier for under-25 in employment to have cheaper transport (and somehow structured so that people who don't want to work aren't able to travel around on buses all day). And in tandem with that, be braver in how we make our towns and cities more sustainable.