What is barely visible is that there is are TWO RN destroyers tied up between HMS CALDER and USS PRAIRIE. Again the War Diary enter for 19 and 20 September 1943 came in useful. It said that HMS OPPORTUNE AND HMS OBDURATE had arrived at about noon on 19 September and moored at buoys. Then early on 20 September they moved and moored to USS PRAIRIE, with HMS OPPORTUNE next to USS PRAIRIE and HMS OBDURATE outboard of HMS OPPORTUNE. HMS CALDER then moored outboard of HMS OBDURATE. At 0835 USCG 707 moored to the dock ahead of USS PRAIRIE, which can be seen in this photo.
The War Diary further states that all three of these RN escorts departed with HMS VICTORIOUS (which had only arrived on 19 September with two USN Flush-Decker escorts) just before noon that same day headed back to the UK.
So this photo firmly can be dated as being taken on 20 September 1943, sometime after 0835 and before noon.
The three RN escorts are painted in similar schemes and USS PRAIRIE is painted in MS 18 (5-N hull and 5-H topside) that is well faded in this photo.