Trademark on Douglas gears?

[Hutch]

Hi All,
I was looking at some early two speed (circa 1915) and three speed 2 3/4 HP gears (circa 1920) recently and noticed what is presumably a trade mark stamped on some of them along with D.B., which I presume to be for "Douglas Brothers". Some of the dogs also have this stamp on them, tho' as they are stamped on a wearing surface they can be hard to read.

The later gears (CW in this case) have the familiar D over stamped with K on them (i.e. Douglas Kingswood) but otherwise appear to be identical. In the attached picture the gears on the left have DK on them and the ones on the right have a stylised version of "VBH" or something similar and D.B. on them.

Does anyone know what company this logo stands for and whether or not Douglas made them under licence, or they were bought in by Douglas?

I have seen  D.B. stamped on other parts such as a Bosch Magneto from 1913 and a Bowden Magneto control lever. I presume that these were bought in by Douglas from these external companies as a job lot  and maybe they were a specific design just for Douglas so were stamped to identify them?

Any clues would be greatly appreciated,

Cheers

Ian