A family comprises 3 boys. Let's call them Fred, Jim and Bert, born in that order.
It's obvious that Fred is Jim's older brother and Bert is Jim's younger brother.
Is Jim Fred's older brother (on the grounds that he's the older of Fred's two brothers) or is he Fred's younger brother (on the grounds that he's younger than Fred)?
Tilly - would Fred refer to Jim as his older brother (because he's the older of his two brothers) or his younger brother (because he's younger than him)?