07 scout  developed very bad oil leak ... the suspect was the rocker cover gasket. Has been replaced twice  by my mechanic who I trust .  He took the car home last night  I picked it up this morning as he drove it to work.   Only a 5 min journey for him .   I drove to work  29 miles parked up  left it.drove home tnight  pulled on the drive could smell oil  had a look under neath and its drenched .. . What else are known culprits ?? 

It should be easy enough to trace an oil leak, start by a thorough cleaning and monitor frequently.

Remove the undertray for a start. You'll never tell with that on. Clean the area under the engine where the oil is.  Old rags/towels and Screwfix's own degreaser is excellent and cheap for this.  You'll need axle stands or ramps to get underneath though.

When clean put sheet of cardboard underneath as you have done and examine for drips.

 

However from your middle pic it does look like the rocker cover, but that is a lot of oil you have on that cardboard.  Just keep that area clean and examine regularly until you pinpoint it.  If it really is the rocker cover I'd be inclined to look for another mechanic.

Also, and pardon the stating of the obvious, keep a close eye on the engine oil level!

 

 

What engine is it? A pic showing the whole of the top would be more useful.

 

If its still leaking from the rocker cover or even elsewhere, it may suggest the crankcase ventilation is blocked (PCV valve?)

Even though there seems some evidence this is a top end leak, it needs to go on ramps and carefully examined underneath, could be sump seals, oil seperator, crankshaft seals (either end), filter housing..or something else.  The amount underneath doesnt equate too well with that picture, maybe multiple leaks if the crakcase is being pressurised, which incidentally could also be due to piston blow by/problems.

 

Should be easy to spot on a ramp with the engine running. Clean up and observe as advised earlier.