I’m a new recruit and I got my uniform the other day, can someone tell me why the wedgewood and dark blue shirts are sooo damn long? Shoulder wise and sleeve wise they’re perfect size but it’s as if it’s just a really long cut for someone who’s really lanky. It nearly goes down to my knees, and I’m average height for a male of my age. 
Is it okay to hem or tailor it in that regard? It can definitely be tucked in as I’ve tried but there’s just so much extra fabric down the bottom
Better to be too long than too short. Plus, you’ll grow!
It’s because they are designed for fully grown adults, not 12/13 year olds.
Is pretty much what I say when cadets come back saying “My mum said this is too big, do you have anything shorter”
I wish people would stop saying that; because it’s not true.
How many “fully grown adults” have you seen who could fit into a size 31 shirt and a pair of 66/68/76 trousers!?
RAF shirts are cut to a length more like a traditional shirt.
These days, fashion has evolved to shirts being shorter in length. Historically they were longer, with curved sides (which cleared the hips), so that the fronts and tails tucked down well into the trousers. That way, the shirt would be less likely to untuck during a gentleman’s daily physical activity.
It just happens that the RAF shirt pattern has evolved little from it’s early roots.
This is the answer.
OP, you no doubt find your school shirt riding up and needing to be tucked in again and again throughout the day?
Proper shirts don’t do that. Your issue shirts are proper shirts.
Yeah I agree with you
Ahhh, I see now, thank you everyone for educating me 
. I’ve only ever worn school shirts which are quite short in comparison
It’s to keep it tucked in so your back stays warm after MOD/HQAC insist that we turn heating off/down to conserve energy this coming winter. Chip hats with the flaps down will also become “de rigueur” indoor wear, as will gloves, woolen, blue (with or without fingers)