“Decants” means people who have been moved out of their Council housing elsewhere. Eg as in when the City of London “decanted” all the residents from their older person’s sheltered housing flats at Mais House. Some of those who were robust enough to survive the upheaval were moved into places within the Borough and some outside, including Brixton. In the case of Mais House residents had been told the “decant” was temporary and they could move back once the building had been refurbished. In fact it’s going to be demolished.
I wonder if “discretionary succession” is where the person who is named in the rent book has died and had adult relatives living with them who the Council won’t transfer the rent book to? I knew someone who had lived in privately rented accommodation in the Borough since 1945, when he was a child. The rent book was originally in his father’s name and was transferred to his mother’s name when the father died, but when the mother passed away many years later the landlord wouldn’t put the tenancy in the son’s name, even though the son had called that house home for more than 50 years and had no memory of living anywhere else.