Bottom Plate ID

[Manstein]

I've just found this bottom plate which seems to have come adrift. I wonder if anybody can recognise its maker? I've trawled through the collection but cant find its parent.

 

[sev-8]

It says 921-M, so I'm guessing it's from a Yates

 

[TobyC]

 

[Manstein]

Thanks chaps it must be the spare plate for the hybrid.