The trouble, mustflywillfly, is the use of the word junior in a perjorative sense (as you and others in this thread have done!). Inevtiably people who care - and love to banter as well - will bite.
I loathed being referred to as a junior officer when I was an old-time flight lieutenant. It's the same here, I suspect.
I couldn't care less, though, whether the RAF is junior or the Navy the senior (or for that matter, whether the Army is the in-the-middle service!), This Senior Service thing (as beloved by those who produce Navy News - it appears in almost every bloomin story!) is something the admirals perpetuate to give themselves a warm feeling of importance.