The UKtransit chest DDE's for the period India recieved VB's shows the 'normal' length transit chest as do commercial Vickers booklets which I would imagine they would have been exported in.As the UK drawings also refer to the conversion of Lewis and Vickers chests I think it is more of a case of 'make do and mend' rather than 'if it ain't broke....'
I would have thought the original boxes would have lasted until the Bren came into service there ? Is there any mention of this in 'The MGO in India' ?
With the 'concessions in war material and construction of wood boxes in service use' in early 1940 giving alternative timber types and reccomendations for reducing timber thicknesses , making a smaller chest would have helped a gread deal in ecconomising timber usage I would have though regardless of mixed fleets ?
Anyway from cost,materials and logistics a smaller chest with less fresh air as per the smaller Indian version seems a good idea , but then again I have had no dealings the govermental procurement !![]()