In Bedford buses have spaces for both pushchairs and wheelchairs with ramps that can be lowered for both. Both spaces are clearly labelled and drivers do ask people to move down the bus if they are sitting in these spaces and someone needs to use them. If there are no wheelchairs then the space can be used by buggies instead but I will always give up the space if I am in it.
However, I have had occasions where people can clearly see me in the queue with my son asleep in his buggy and shopping and they still sit in the pushchair space. I have also heard the older ladies saying ' in my day we had to fold them down . .' criticising me for using the space. If my son is awake, I will get him out and fold the buggy down so he can sit on my lap or on the seat ( he is 2yrs old ).
Tha way I look at it is this - if pushchairs were not meant to be on buses there would not be a designated space for them.