The first letter code looks like an ’S’ to me.
If the code is indeed G1+HP then it could be the second He 111 with that code. The first G1+HP was He 111P-2 of 6./KG55 that was shot down on May 13th, 1940 and destroyed. The second He 111 coded G1+HP was shot down over England on August 16th, 1940 and captured intact. It may have been the aircraft flown by Gerhard Pulver.