After the coming into operation of any development plan in any area, no person other than any State Government or the Central Government, or any local authority shall use or cause to be used, any land or carry out any development in that area otherwise than in conformity with such development plan:
Provided that the continuance of the use of any land for the purpose and to the extent for, and to which it is being used on the date on which such development plan comes into operation, may be allowed for such period and upon such terms and conditions as may be specified in such development plan.