Earlier today, whilst searching through the ZSL Daily Occurences Book for 1974 (investigating something completely different) I noticed, by coincidence, that London Zoo purchased a pair of zorillas from Colchester Zoo on 5th September 1974.
I don't know if they were the same zorillas listed as being at Colchester Zoo in 1972 but I thought it worth recording here.
Thank you for finding this information. While it definitely isn't certain, I think they could well be the same animals, unless of course Colchester were successful at breeding zorillas (not that I have found any information that suggests this ever happened).