Pre-war and early war BSA used full rubber oil lines while the later war BSA's had copper pipes with rubber connectors. The brass ferrules are not original.
Thirty years ago I got some stainless steel braided teflon lined oil lines made up with slip joints at either end so so they are a doddle to remove & replace.
Only place the bike does not leak.
Against the allow the now quite dull braid is invisible.
I bought NOS oil pipes from Russell Motors years ago and the rubber connectors were fitted with a brass ferrule at one end and a pipe clamp at the other...I've come across this type many times...So, as usual, there seems to be more than one answer!....Ian