TD5 breather question {year 2000}

Question for those in the know....

Just completed a 5hour non stop trek to the inlaws, held a steady 60 / 65mph all the way so not thrashed it.... parked uplast night, this mroning small pool of oil {poss around table spoon full} on the road under the TD5 {year 2000}, looked under and there is a small 3 inch breather pipe mounted on the engine under the starter motor... this is where the oil appears to have come from, is this an engine breather ? crackcase breather ? gearbox ? fuel breater ??

Have googled it but cant find it and my trusty {although bit crap} Haynes manual is at home..... just interested as it has never breathed this much before...

{also posted this in Defender section }

cheers

Jay

that is out of starter but would think its leaking above that and running down ,could be diesel out of fpr on rear drivers side of head or rocker cover ,remove engine cover to look

Nothing appears to be coing from the head or rocker... all very dry... it looks like its from the 3 inch pipe located under the starter motor.... bt where does that breath for ? ?