This was originally posted on the GPR Facebook page but I wanted to share the information here too.
The first photo is taking looking forward towards the cockpit and shows a motorcycle combination loaded into the cargo hold with two airlanding troops looking on, a Royal Engineers unit indicated by the '49' on the sidecar. The photo also shows the cockpit doors in closed position.
The second photo shows a load diagram for the Horsa showing a Jeep, trailer and motorcycle combination. Thanks to Luuk Buist for this image.