An attendance order made in respect of any child shall, subject to any amendment thereof made by an education authority or variation made by the sheriff, and unless revoked by an authority or annulled by the sheriff, continue in force so long as the child is of school age:
Provided that if a decision of an education authority under the Act of 1946, the Act of 1962 or this Act that a child requires special education is revoked any attendance order requiring the attendance of that child at a special school shall be deemed to be annulled.