Håkan -
Your "lake" is on my map as Al Maghrah. It was that "a" instead of an "o" and that extra "h" on the end that mislead me before. On my map the name is spelled in the color blue, which probably indicates a water source (oasis). Bir el Abd is also at a water source with the name
Balātit el Kish. Mine is about 63 km WNW of yours, so that would be too far away for consideration. So the Italians must have had a landing ground at Al Maghrah that was never used as such by the British or the Germans. Here is another tool you can use - see grid squares 35-8 and 35-14:
http://www.lib.utexas.edu/maps/ams/north_africa/
L.