Mortgage rationing...

I just came across an abstract for a paper (“The Ending of Mortgage Rationing and its Effects on the Housing Market: A Simulation Study”) published in 1989. It says: “. A consequence has been that households are no longer generally subject to mortgage rationing.” - This was puzzling to me because I never knew that we had any mortgage rationing… maybe we never did, maybe the author was just being metaphorical.

My question is actually more general: Does anyone know of any periods in any countries where thare has been mortgager rationing. And if so how did it work and what was the reasoning behind the policy? If you happen to know about the status in the UK then that’s even better..