Parker Knoll are an old, well-established furniture make of good repute.
These two chairs are Model No PK717.
I'm not sure just when they were made, but according to other adverts anywhere between 1930s-60's.
The frames are in good condition with just some scuffing and scratches, but none of them deep.
The original fabric is worn and needs replacing, but they come with a more recently-made set of custom made covers (light floral pattern - not shown in these photos), which are in good condition, so the chairs can be used as they are.