Royal Signal corps bag identification

[The History Detective]

I've had few items come in they all appear to be Royal Signals related. Can anyone help me identify a padded bag, the stencilling on the top reads:

JACKETS BATTERY SECONDARY
PORT No.4
CAT No ZB 10467
R.M.C. LTD 1945

It has 2 threaded bolds with butterfly nut for attaching to something a vehicle perhaps. Any help would be gratefully received.

[The History Detective]

Having had a think about this I have come to the conclusion that this is one of at least 8 packs for a large communication device and would have housed a battery and would have been secured with studs/butterfly nuts. So I am nominating the trailer mounted tactical wireless set No.10 I'm also assuming the legend 'JACKETS BATTERY SECONDARY' refers to these being back-up batteries should the generator fail.

Anyone else have any thoughts.... I have emailed the Royal Signals Museum for their input I'll post here if they reply.