F
Frosty
Guest
The Prayer to St. Michael was not always part of the TLM. It was added to the Mass in 1886. Also, the Prayers after Mass were only said after Low Masses.It was always in the TLM…and in this age, we must not forget him.
.The prayers after Mass of which it was a part were said after private Masses or Low Masses. They were not said after after a sung or High Mass, a Mass said with any special solemnity (e.g., a funeral Mass, conventual Mass, First Communion Mass, ordination Mass, a wedding Mass, Mass of a newly ordined priest) or at a Mass followed by some other sevice if the priest does not leave the sanctuary
Catholic Encyclopedia