[78-L] British Vocalion Swing Series

[Tim Huskisson]

Does anyone here happen to know what the significance was of the C-xxxx
catalogue numbering of some of the British Vocalion Swing series issues?

For example, 

Vocalion S-81 (Benny Carter and the Ramblers - New Street Swing/I'll never
give in) was also issued with catalogue number C-0013.

Label designs appear to be identical. Were they for export?

Best regards,
Tim Huskisson