Subsunk;
Not seen the film yet, but from the context of the posts here, it could be that Rickman's character has made an operational descent - the protocol for people who do that is that they are authorised to wear their para wings on the left breast instead of the right shoulder.
Obviously we don't see many of those these days but it was commonplace during WW2.
If Rickman's character is ex-Special Forces, they tend to put up the basic jump wings instead of SF ones on uniform to avoid drawing undue attention to themselves
Utter tosh on all three accounts!
It took a number of operational jumps to be entitled to wear the wings on the chest.
It was not commonplace as operational jumps weren't that common.
It's not a 'tendency' at all.
However, elsewhere;
Captain M.E. Anderson, SAS Wings, South African Pilot wings, member of the SBS
SAS SA SBS Pilot - Great Britain: Militaria: Badges, Uniforms & Equipment - Gentleman's Military Interest Club