I have a quick question.
I recall an old key profile used in Australia. The head is the same shape as a C4/LW4 key but the groove is different. It is not the reverse C4 profile (or a lane/astra -- they have a different head usually).
I believe that they were used commonly many, many years ago. I found that mostly on Lockwood 001's or night latches around here, and found the occasional one on an oval cylinder and lockwood door knobs (530 cylinders I think).
Do you know what profile it could possibly be? I found it in old Australian locks a few times (which are like 15-20 years old?). Sorry but I don't have any pictures.
I don't think they're restricted either. From memory it reminds me of the J series keyway (however, I never tried a J series key in the lock of the question to see if it fit), but they usually have a MLA head, which these keys do not have. And certainly the keys do not have restricted markings (eg. "Do not copy") on them.
Would anyone know profile what it might be?