In 1975, Squadron Leader Tom Sheppard led the Joint Services Expedition on the first west to east crossing of the Sahara Desert, from the Atlantic Ocean to the Red Sea—a trek that covered 7,500 miles and took 81 days coast to coast. The team used four of the very first production forward-control 1-tonne Land Rovers, two of which were equipped with powered-axle trailers driven from the rear PTO of the vehicles. In addition to completing the route, team members conducted a series of gravity measurements along the way, collected minerals, lizards, and bilharzia-bearing snails for researchers at the British Museum, and experimented with navigation techniques combining astro-fixes and sun compass bearings with calculations provided by what was then a cutting edge piece of technology: a Hewlett-Packard HP65 programmable pocket calculator. 

Sheppard, already a desert veteran by that time, nevertheless learned much that would stand him in good stead on numerous solo Sahara treks by Land Rover and Mercedes G-Wagen, knowledge he subsequently shared through such books as the seminal Vehicle-Dependent Expedition Guide and Four-by-four Driving (not to mention his more introspective and lavishly photographed works such as Nobility of Wilderness and Quiet for a Tuesday: Solo in the Algerian Sahara).