Good evening,
I think you are correct Trevor, I'm sure that even in the present day ships are dressed fore and aft in port for special occasions. Whether or not what is shown actually means anything I don't know, probably like the picture, a load of gobbledegook.
Just for the record, using a flag set from 1913, the flags shown are as follows starting from the bow;
Preparative, F, UNION JACK, U, E OR PENDANT 1, X, 2, N?, 3, 4 (upside down) PENDANT 4, UNION JACK, D?, H?, *, V, *, 4 not fully visible, 9, PENDANT 8, A OR 6, INTERROGATIVE, 5, Y, PENDANT 4, *.
The numbers are square and the pendant numbers are the long pointed flags. The asterisks are flags that don't appear to be on any list. Iv'e used the 1913 set because that's the only complete set I can find or make sense of. The 2 larger UJs near the bow are actually on shore.
If there are any ex navy signallers out there, perhaps they could give us their professional opinion.
John915