RAF 73 Sq. individual aircraft identification letters

[drifter206]

Hello all

I am trying to find individual aircraft letters for two RAF 73 squadron Spitfires:
1. 02.03.1944. Spitfire LF IX (EN 582) Dennis Draper - KIA (near Slano, Yugo)
2. 03.03.1944. Spitfire Mk Vc (JG 783) Charlie Hayne - POW (Orašac, Yugo)

I have Don Minterne book (history of 73 Sq. - vol 2) and in there he mention these cases but he didn't include "letters", only serial numbers
Also in AIR for 73 Sq. there is no mention of letters.
Is there anywhere I could try to find (log books …) information regarding letters.
Could you also explain RAF Sq. A and B flights. I read somewhere that there were two flights per squadron. RAF A flights would get letters A- ? and B flight letters ?? Were Draper and Hayne in A or B flights?
As always thanks in advance
Antun