Well, i'm looking at my forms for BRNC i received today, and it says as i have stated above. Sub-lt are promoted to lt on completeing 3 years seniority as sub lt. Further promotion is on a credit basis.
No degree, you enter service as midshipman with no seniority unless u have HNC or equivalent, whereby you have 1 years seniority.
When you/if get to BRNC you'll get divided into "Groups" these are strictly 32 people. Within each "group" you will be sub divided again into "table groups" these are 8 people strong. So you have 4 "table groups" with the left over number in a temporary rolling role of "Group co-ordinator".
The Group Co-ordinater is temporary role and each student is accessed on their performance and will be expected to complete this role at least 3 times whilst a cadet at BRNC.
Within each table group there is a strict, yet, changing hierarchy. One week you may find yourself the mustard monitor, the next you are the salt sentry. Each and every role is different but all are important.
Enjoy Your time at BRNC, take your time "in the Piccalo barrel" with a "pinch of salt", smile when the "Chips are down".
Just remember, The junior ranks, especially the Marines are there to help you.