The British Central Landing Establishment developed all manner of drop panniers, containers, valises, and packing crates for the paratroops to be able to jump with their weapons and equipment. The topic is too broad to discuss here but as they developed containers for rifles, Bren Guns, PIATs, mortars, Welbikes, radios, blood supplies, ammunition, and P37 web gear it's almost a cert that they adapted some to drop No.4 MkI (T)'s. One drop container held 12 rifles and a 1,000 rounds of ammunition, the C.L.E. Mark I container was over 6 feet long and could carry 246.5 lbs. of equipment with the standard 28 foot parachute. David Gordon has a whole chapter devoted to supply dropping in his excellent book "EQUIPMENT OF THE WORLD WAR II TOMMY" Gordon's books are must buy for any serious collector of British Commonwealth weapons and kit.
I seem to remember reading that there was a 'padded carry bag' developed which was actually carried across the chest during the 'jump', and was dropped on a tether just before hitting the ground.
Was that for the No5 ?
Mine are not the best, but they are not too bad. I can think of lots of Enfields I'd rather have but instead of constantly striving for more, sometimes it's good to be satisfied with what one has...