Jolli Joe (the UK Uke)

Jolli Joe (the UK Uke)
Jolli Joe is a bit of an enigma. They are all metal, (possibly cast), painted Blue, and they have a label on the top that says "Jolli Joe the UK Uke".

They are pre WW2, and still fairly common. The only firm date I have found is one in a 1935 catalogue from the Birmingham distributor F. R. Martin. There is no maker's markings other than the headstock plaque and they don't appear to be from any of the major UK Banjo factories. However, whilst a lot of them come with their own faux crocodile case, I have seen a few with a more standard John Grey case, and though it doesn't directly say it is one, F.R.Martin only distributed John Grey Banjos? If they were part of Rose Morris, (who owned John Grey at this time), I don't think they came from any of the usual London factories?