The database of
Mosquito claims for enemy aircraft has a claim for a Ju 88 but adds this:
More likely to have been Do 217 M1 6045-U5+GK of I/KG 2. Patrol time 23.35-01.20, time of claim 23.59. E/A may also have been of 3(F)./122, which lost a Ju 88 during a Nachtbilderkundigung (night reconnaissance) of the English southeast coast on 27 July. Pilot:Lt Robert Ziegler, Obs: Oblt Walter Salecker, Ofw Heinz Gärtner and Uffz Albert Rippel all KIA. However, as all were buried at Nieuwe Ooster begraafplaats at Amsterdam on 17 Aug 43 (Uffz Rippel washed ahore on the beach of Noordwijk on 14 Aug 43), it seems that their aircraft crashed just off the Dutch Coast, as all were recovered/washed ashore. 430669 Ju 88 D-1 7A+BH 1.(F)/121 (Luftflotte 3) OPS (F) missing (100%) unk location (PLQ´22-71-4´) 27.07.1943 (crew of 3.(F)/122: F Lt. Robert Ziegler, B Oblt. Walter Saaleger, BF Ofw. Heinrich Gärntner and BS Uffz. Albert Rippel missing.
That still doesn't seem to fit with an 'S' map reference. I see from the 'Record of Events' that they were controlled by GCI Sandwich so they would probably have started out in the British Cassini Grid which had square 'wR' at the bottom righthand corner, off the Kent caost. It seems there was no 'wS', although it would have been in just about the right place.