Seems like duffel and kit bags are not dissimilar, both being used to stow things in and there’s a host of modern fashion versions on the market nowadays. The one we have here in the collection is of military origin (we’ve found a similar one on the internet relating to the Royal Australian Air Force), and bears the War Department Crows Foot Logo as in the picture above, the picture also seems to indicate it was made/issued in 1953 – a time when GB still had National Service and servicemen/women would probably be issued with one of these to stow their kit – hence kit bag!
Lots of excess military gear was sold off when no longer needed and this one was probably bought in a 1950s ex-army store. Thanks to Ken MacTaggart for donating it, full of kit which you’ll find elsewhere in the collection.