My thanks go to Sean Featherstone for his help with identifying tonight’s object. I picked up this light canvas bag for a pound a few months back and beyond recognising the SV code on the lid as being something to do with munitions I didn’t have a clue:

Happily Sean was able to identify it for me as being a bag for 51mm mortar ammunition. This bag was a disposable grab bag that held six rounds, as seen in this period advertisement:

There would have been a polystyrene inner to hold the rounds, now long since gone, and it was then packaged into a metal ammunition box before being handed out in the field. The bag is light in construction, made of cotton with a webbing grab handle:

This strap has a short part to allow the bag to be carried in the hand, and a longer strap to allow it to be slung over the shoulder. The webbing goes right under the bag and is sewn to the sides to help support the weight of the contents:

A small brass eyelet is fitted to the base to allow water to drain out:

The top flap is secured with a piece of Velcro:

The only markings are printed on the top flap and consist of the code SV3407 and something faint underneath that might be the number 86 giving a date of manufacture or filling:

This is one of a number of different bags issued for carrying 51mm mortar rounds. This was the simplest and cheapest. There was also a more durable cordua nylon bag that was refilled from the ammunition boxes and was not a disposable item as can be seen in the photograph above.