I am a little confused with the RAF damage classifications on Tony Wood's site. He has
Cat 2 and
Cat 3,
but according to this site
http://www.rafjever.org/glossary.htm Cat 2 and
Cat 3 are used from 1952 onwards. Up to 1952 letters were used.
File being looked at,
RAF Fighter Command. 1st Jan - 31st Dec 1941. Issue 30/7/04.