My interpretation is that the retained lands in this case will probably relate to the 'common grounds' which is an land owned by the OMC.
Basically if you are within the boundary of the estate and standing on the common grounds which is any accessible space, green or path within the estate and the dish is visible then the OMC would be within their rights to remove it. (assuming its a common building element.).
If the dish can only be seen by accessing private property not associated with the OMC or on adjacent land or property then my understanding would be that this is OK and within the conditions of the lease.