I checked on the Petronella website, and they have provided excellent photos of the lower level exterior, lower level interior and table area, and a visible door marked "handicapped toilet" so my assumption would be that... More
I checked on the Petronella website, and they have provided excellent photos of the lower level exterior, lower level interior and table area, and a visible door marked "handicapped toilet" so my assumption would be that they have the ability to accommodate wheelchairs.
Trip advisor has the link to the restaurant website on the Petronella trip advisor main page if you want to access the photos.
One thing I did notice was the that Butter Slip (a kind of tunnel pass through between streets) has cobble stones and also stairs, so I think someone would have to have assistance navigating the wheelchair.
Unfortunately, I can't comment on the upper level as we were seated on the lower level.