1973 was one of the quieter years for UNIT in the early 70s. There were several incidents in which they were involved, but these were relatively low-key affairs. Even in their most publicised role, guarding the Punk Convoy, they played a low-key role
In January 1973, UNIT UK faced the most severe crisis in its history, being shut down for several days with no guarantee that it would restart. This started with government cutbacks. Faced with severe budgetary restrictions, the Ministry of Defence was looking to cut anything that it felt unnecessary. UNIT was an obvious target - being a UN force dedicated to unusual incidents with a high upkeep cost.
The MoD Secret Vote Finance Committee decided to transfer responsibility for the events UNIT dealt with to the Royal Marines. Obviously Brigadier Lethbridge-Stewart wasn't going to just lie down and take it, but none of the authority figures that he had contacts with was both willing and able to apply pressure where it was needed. UNIT UK did actually survive, but it did so by the skin of it's teeth.
The first thing helping UNIT to survive was a major cock-up by UNIT's replacement. Under Rear-Admiral Zecca, the Marines transported a prisoner from UNIT HQ to the Marines' HQ. The prisoner, officially described as a Foreign Hazard, just disappeared from an army truck in the middle of a large and heavily armed convoy.
The other event which led to UNIT UK's continued existence was the provision, apparently by the UNIT Doctor, of an extensive manor house just outside London. This new building was used as a rent-free headquarters for UNIT, replacing the rather expensive Central London building they had been using up till then.
The first incident convinced the committee that UNIT were far more competent than the Marines, the second convinced them that they could maintain UNIT forces at a much reduced cost. UNIT was, therefore, free to continue to deal with the various bizarre events that kept on happening, from mad scientists and psychic phenomena to possible extra-terrestrial activity.
During May and June 1973, UNIT were assigned to keep an eye on a convoy travelling through the South-West of England. The convoy was following a mysterious and unnamed band who first performed on Dartmoor. This first gig coincided with a riot at nearby Dartmoor Prison, the brutal murder of three Prison Officers who were escorting a work party, and the brutal murder of a policeman who had been passing. Their next gig incited the brutal murders of three fox-hunters who had chanced upon the venue, and whilst they were stopped at Glastonbury two Policemen who had been keeping an eye on the convoy went mad and brutally murdered their wives. In all cases, the murderer claimed to have no memory of the events.
UNIT's task whilst it was guarding the convoy seemed to be not to disband the convoy, as might have been sensible, but merely to observe, and limit contact between the convoy and the general population. They failed to stop the - probably related - wine bar massacre in Bristol. This was an attack on an executive wine bar perpetrated by a group of local alcoholics who hung around the graveyard where the convoy had recently stopped. However, they - together with local police - did prevent clashes between the convoy and a pro-country sports demonstration. Incidentally, on that same day, Princess Mary murdered a potential assassin in a manner very similar to that of the other convoy-linked murders. The would-be assassin was soon discovered to have extensive links with Jeremy Willis, then the Shadow Transport Secretary.
The convoy came to an end on the night of the 20th to 21st of June. The convoy had split - half of it was headed for Salisbury Plain, and the bulk of the UNIT forces assigned to the convoy deployed around Stonehenge. Meanwhile, the other half of the convoy headed for the nearby village of Cirbury - which had its own stone circle. There was a pitched battle between UNIT and the convoy at Stonehenge, and the band's performance at Cirbury was interrupted by a small squad of UNIT troops. The details of what happened are unclear, as those present seemed to be in some kind of daze, but it is clear that the band either died or disappeared, along with their influence, during this gig.
After this incident, UNIT's year was relatively quiet. UNIT's operational history consistently shows that they alternate between times when their resources are stretched to the limit and times when they have nothing much to do for long stretches of time.