I can’t remember any such embargo and can remember some people being taken on to fill vacancies, although that might be just before or after such an embargo. As said above, BR was given an overall budget and left to get on with it, but it is possible that it might have trimmed back a bit in places after listening to the government’s pronouncements. There were always the equivalent of local embargoes in places where a cut in staff was expected: areas where manual signalboxes were being replaced by power boxes, depots that were going to lose a lot of work due to a customer closure, etc.