I wonder why Jaguar added 2 breather’s , top of the cam covers , on there XK Military engines , think they did the same on there racing engines , with the size of the breather pipe on a normal engine , can’t see pressure building up , and the head is linked through the timing chains , maybe it just look’s more impressive 
Maybe oil mist catch is more effecient this way … ?
military off-road spec demands certain extra things, including additional spark suppression, more water proofing, ability to work at an angle, greater reliability and safety factors.
not sure where that fits in with those big breathers though
Interesting - perhaps to extend time between oil changes?
I think that’s the key to it all. The military version also had a special oil pump, didn’t it? Maybe the military just wanted “the best you can” including a better oiling system complete with PCV. Needed or not. Maybe less mist back there.