Hello again Bertrand
No, it's definitely an H. Perhaps your A is a deformed H!
The form I have is a 'Personal Combat Report', or Form 'F'. The information has been added using a typewriter, and it's a good photocopy, so it's clearly legible. Under the heading 'Type and mark of our aircraft', the entry is 'Spitfire IX H'.
I'm of course guessing the H doesn't refer to the type or mark of Spitfire?
Best regards
Simon