The main elements of an Airborne Division were the two parachute brigades, which were made up of three parachute battalions from the Parachute Regiment, or provided by the Canadian Parachute Battalion.
The first Parachute Battalions were formally established in September 1941.
They did not initially have any medium machine gun capability but are included here for completeness. Over their iterations, the battalion did have a variety of weapons, including the Smith Gun (a smoothbore 3-inch breechloading gun).
The medium machine guns were first included in the February 1944 War Establishment as an optional addition. There was the option to use one of the two mortar platoons as a medium machine gun platoon of four guns.
It’s known that this was the case for a number of battalions during both Operation OVERLORD and Operation MARKET GARDEN.
A full copy of the detailed War Establishment is available as a PDF download.
Based on the example of 156 Bn, Parachute Regiment, the machine gun platoon that served in Operation MARKET GARDEN (Arnhem) was as shown below.
To understand more about the roles in the Platoon, please visit the man-carry pages. They were dropped from aircraft by container or, later, leg bag.