Hi All:
I readily confess virtually no knowledge, let alone any expertise, of these sorts of British cuffs.
But, I would like to suggest one thing to any of you out there who wish to research them.
Do not limit yourself just to patents, trade advertisements and the like. Also, don't restrict yourself just to the folks who applied them, the law enforcement types.
Go talk with some criminals. Try to find the people who were on the receiving end of these items. After all, for every cop out there, with whatever type of cuff used, that one guy used them many, many times on many individuals.
Yes, trying to interview a prison guard from Parkhurst in 1942 will be next to impossible today; but trying to find and interview one of the many incarcerated there at that time might be a more realistic approach, and perhaps more introspective.
After all, if it weren't for those criminals, why have handcuffs? By being cuff collectors, we owe a debt to those criminala; were it not for them, we would have nothing to collect. So, why not find them and talk to them?
In my own experience, quite honestly, I've found ex-convicts to be a much more entertaining bunch to be with than Sunday School teachers, university professors or insurance salesmen. And they're easier to find, being more plentiful; well, other than insurance salesmen.
Franklin