According to ZIP/No. 892, 'GAF Sea Reconnaissance (Home Area and Atlantic) for 7th August 1943' (TNA HW 13/36):
No indications of Heavy Fighter Patrols by V./KG 40 (LORIENT-BORDEAUX).
G.S. active 1523–1524.
I think G.S. means ground station. Times are BDST.
By the way, I'm having real difficulty reading the type as a Sunderland, even allowing for the free-for-all that was German handwriting of the era. The first letter looks far more like a Sütterlin uppercase L than an S, the fourth letter has a descender (which a d shouldn't) and the fifth looks like an i and what should be an r in 'Sunderland' also has a descender. I've no idea what it does say though.
Even after some photoshopping I can't get the claimant's name any clearer although I read the initial letter as more like a V, W or X. Since there is no dot for an i or stroke to indicate a u, what about Werner or Wenner?