In your first sentence, you say this change relates to visitors’ permits not to residents’ permits.
I live in a road which has a residents’ parking scheme. If you are over 65, you are entitled to one free resident permit for your own vehicle. The cost to those under 65 is £26 per year.
If you do not need a resident permit you can buy a visitor permit instead at a cost of £26 per year. This must be allocated to a particular vehicle and allows on-road parking for up to four hours. The cost of the visitor permit applies irrespective of the age of the resident or the visitor.
You cannot buy a visitor permit if you already have a resident permit. Instead you must buy visitor tickets. They cost:
£5, which allows your visitor to park for up to one hour
£15, which allows your visitor to park for up to four hours
£20, which allows your visitor to park for up to six hours
As with the visitor permit, charges apply irrespective of the age of the resident applying for them or the age of the visitor.
Perhaps your local authority is bringing its scheme into line with other authorities.