you should be able to request the information you want from the council. I think its now out of VM hands until you right with the council. The council gave permission for its placement and VM did as was granted, If the council granted the permission and shouldn't have then you need to take that up with the council.
If Vm installed it in the wrong place the council need to contact VM to correct it. But i suspect that you will get no where, the road outside your home if belongs to the council so yes if it is not on the deeds as access they can allow anything to be installed outside.
this will come down to how the lowered curb permission was granted. Its possible it was done and the council never granted any kind of access rights.
That you, I will ask my patents to seek the council paperwork.
From ready the laws and picking up on one of Kaths point they defiantly okay to have the drive. No extra paperwork or permission was granted. Therefore I suspect it is a matter of the council and VM tieing their paperwork up so we know what is what.
Looking at the Street map the cabinet is in a typical position for street furniture adjacent to the property division line between two properties. I can take a short walk from my house to the shops and see a dozen lamp posts and telegraph poles in the same relative position. Bear in mind when installing street furniture the installers will have no idea of any future works unless planning permission as been applied for before the installation works.
It looks like your main problem is the boundary fence on the right of the streetview photo, which does not give you much room to get a full width drive in.
I am suprised this was not checked before the drive was installed. The position of the cabinet should have been included in any planning permission drawings, and to be honest if those plans were submitted before me, my first concern would be how you were going to protect the cabinet from accidental damage.
If this was a lamp post in this position then you will need to pay the Council to relocate it, I would expect it will be the same for VM.
I agree that your best course would be to talk to the Council explaining your mother's accessability needs.