Did UVF veto army massacre plan?

Remarkable testimony from the Pat Finucane Centre at the final day of the hearings on the Barron Report into the Dundalk bombing of 1975:

When we met John Weir, we asked why there had been no retaliation for the Kingsmills massacre. His response was that a retaliation had been planned on the primary school at Beleek. He stated also the attack had not been carried out because the UVF leadership in Belfast had objected, rather than because those involved thought it would be a step too far. The UVF leadership believed the plan itself had come from a certain member of the Glennane gang whose name is known to us.That person was working for army intelligence. We were told that in essence the plan had been an army intelligence one. We were quite shocked to hear this, but have never publicised the fact
that we knew. We did, however, suggest to the BBC a year and a half
ago when it did a programme on the incident at Glennane, that it
interview another member of the Glennane group and former member of the
RUC and ask him about the accusation. That person admitted on air that
the plan existed but had been abandoned because they felt it was a step
too far. There have probably been many plans by all sides in Northern
Ireland that would horrify us and that would best be put in the dustbin
of history. However if a plan came from Army intelligence, we have the
right to know that. It is an example of the many issues that still
require investigation. (Oireachtas report)