Leck was a secret airbase in Nordfriesland, Germany where 7 Staffel KG 76 was headquartered in May 1945. Willi is identified in the back row. Standing on the far left is Staffel Captain Hptm. Schillinger (my mother's maiden name). From the map you can see it is close to Klixbuell and Flensberg, on the North Sea.
From Life of WLK, Willi tells us how he arrived there:
The commandant of the RLM facility in Grossenhain, near Dresden, where we stayed for a few days, called us four pilots to a meeting on April 17. He told us that the facility would be blown up, that Russian and Allied forces had joined hands at the Elbe River some 100 miles further up, and our five jet planes, four AR 234s and one ME 262, had to be flown out the next day. The Arados were to go up North to KG 76 at the Schleswig airfield, the ME 262 to General Galland at Munich Oberwiesenfeld. I decided to stay with my good friends Waldemar Pollok, Kanngiesser and Winkler who decided to take the northern route. Early the next morning we took off. A low ceiling but open skies in Schleswig made me climb through the clouds, landing 52 minutes later at my destination.