ok, here is the answer:
The Airconditioned coach of Frontier Mail at Ratlam Junction. The notings on the reverse of the photgraph says ‘Ratlam Junction’ 11-9-42
The notings on the reverse of the photograph says ‘Ice for the air conditioned coach of the Frontier Mail -1’ Bayana Junction, 11-9-42
**The notings on the reverse of this photograph ’ This is the last piece!', Bayana Junction, 11.9.42 **
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what a basic, crude and practical way of coolings a coach. these ice blocks wud melt by the train’s next scheduled stop where more ice blocks wud be loaded :)**