Terminating deposits were a form of savings-and-loan that were one of the key products of the early building society[1] movement in the UK and from there they spread through what is now the Commonwealth.
So why would anyone join a scheme where you might make deposits for 20–25 years and never receive interest on them and simply get the amount you had saved back at the end of the period?
Accordingly, the terminating deposit product had to be designed in such a way that it did not depend in any way on the wider financial markets and in particular it did not involve any borrowing by the building society which promoted it.
Whilst working-class families aspired to own their own home, they didn't have access to the banking system, and they could not realistically expect to save enough in their working life to buy one.
The reason appears to have been that they relied heavily on the integrity of the organisers and, if this was not present, they were open to many abuses which left depositors out of pocket or dissatisfied.