A Planning Inspector has ruled that a flat created above retail premises did not need planning permission but was acceptable development under the General Permitted Development Order - under class F(a), Part 3, Schedule 2.
This did not relate to the more recent changes to the GPDO that allow signifcant changes of use from office to residential use via a "Prior Approval" process but to the long-standing provision that the upper floor(s) of a retail unit could be converted to single flat (prior to SI 2012/2257) and more recently to two flats (following SI 2012/2257). As such development is permitted under the GPDO then no planning permission at all would have been required - not even a prior approval notice. (This raises the question of how there could have been a Planning Appeal, except against an enforcement notice - we are still looking to try and find more details).
The change had been opposed by the local council on the grounds that "the flat and retail uses would have to comprise a single planning unit" to beneift from the GPDO rights.
In allowing the appeal the inspector is reported to have noted that "Class F does not stipulate any common relationship between the occupiers of the two individual flats or the shop" and that "the concept of a mixed use, which is not defined planning law, woudl miltate against development having to comprise only a single planning unit" (as reported in Planning magazine - subscribers only).
Compass Reference 200-002-179 - search to see abstract.