It's a throwback to pre-unification. In the pre 1968 days all persons in the Naval uniform wore naval buttons (they were different depending on whether you were a PO a Chief, an officer or a Flag Officer) regardless of your trade...you were all members of the RCN. Same thing with the Air Force. You wore your trade badge and your rank usually carried what specialty you were....Leading Telegraphist Bloggins. When unification happened the RCN and RCAF ceased to exist, but the Regiments and their buttons and bows survived. We all went into the jolly green jumper and wore the buttons with the lions on them if not a member of a Regiment. We went to Branches for trades in the same way the Army had prior to unification and regardless of what element you were working with your cap badge showed what Branch you belonged to. when we went to the DEU (mid 1980s) we kept the cap badges and branches but went back to buttons being specific to the colour of uniform. For my money we should have gone back to everyone in Navy and Air Force wearing the element cap badge and designating the trade only with the badges. I think originally the ruling Conservatives (Mulroney) wanted to reestablish the three services as well as the three uniforms but the cost was prohibitive.
