The Cold War.

During post-war the sites of the two bunkers were subject to intense attention from competing interests. The emergence of the military threat posed by the Soviet Union and its Eastern European satellite states in the late 1940s led to the realisation that the civil defence infrastructure which had been so quickly run down after the end of the war was necessary again. The Civil Defence Act of 1948 and later regulations made under that act, required local governments to make provision for an infrastructure capable of carrying out the functions of the wartime ARP * units; at the time, any future war with the Soviet Union was expected to be very similar to the previous war with Germany.
Kenton Bar was unique amongst Regional War Rooms of this period in that it occupied an earlier structure, rather than a purpose-built facility: it seems likely that the existence of two suitable structures with existing secure communications links was too good an opportunity to miss. In plan, the purpose-built regional war rooms were very similar to the Fighter Command Operations Room bunker, being focused on a central two level map room with observation galleries. Council proceedings of 1952 record the purchase and fitting out of the Filter Room with a purpose built Sub Control room being built at Heaton. (Location and details unknown)
The life-span of the Regional War Rooms appears to have been quite short, though details are unknown. By the time that most of the purpose-built structures were nearing completion in 1955-6, the advent of nuclear weapons had led to an enormous change in the perception of the threat posed by the Soviet Union, and the needs of Civil Defence. The threat now was of complete breakdown of central government with the Regional War Rooms being superseded by Regional Seats of Government (RSG), fully autonomous regional command centres, hardened against nuclear attack.
Some of the purpose built Regional War Rooms were adapted as RSG's, but this was not the case with Kenton Bar which did not have the room for expansion required for the increased number of staff. The exact date of closure of the regional war room is uncertain although it is thought that most of these facilities had been supplanted by RSG's by around 1960.
After its use as a war room ceased it was used as a training centre for RSG and later Sub Regional Control staff in Region 1. The presence of materials related to Exercise ARCADE (ROC run exercise) confirms the continued use of the bunker. Sub regional control units were on a smaller scale than RSG's meaning the Kenton Bunker could have been used. However; it was deemed too near the City centre target area for use as War HQ for the Newcastle Sub Region, remaining dormant with occasional staff training until about 1965, after that date it was used for storage for the government offices on site.
In 1968 it was considered for use as a temporary Sub Regional Control until a purpose built one could be built in Hexham however nothing came of this. It remained in use until the stand down of Civil Defence in 1968 after which date it was retained on care and maintenance as the County Borough War HQ. In the 1971 Home Defence Review it was still officially performing this role and in 1974 it was transferred to Tyne & Wear County council. The newly formed Newcastle District Council officially designated it as their war HQ but nothing was done to it due to the Council's extreme left wing policy on Civil Defence and their refusal to pay rent to the Home Office. They instead used the sub basement of Sunderland Civic Centre letting Kenton Bunker remain dormant. Later in 1982 the Sub Control in Heaton was designated as Main War HQ.
In 1986 Tyne and Wear County was abolished and the newly formed Tyne and Wear Fire and Civil Defence Authority wanted to turn the filter room into a modern emergency centre, a scheme that was halted by the end of the cold war in 1989.

* ARP.
Air Raid Precautions were designed to reduce the damage and casualties from air raid attacks by German bombers. ARP included the use of gas masks and shelters, air raid warnings, blackouts and evacuation. Thousands of ARP wardens, auxiliary firemen and other members of the emergency services, such as ambulance drivers and first-aid helpers, were recruited to help ensure public safety and deal with the aftermath of the bombing raids. Together these organisations made up the Civil Defence Services.