2005 S Type 2.7 D

Hi, I've had mine for a year, now, had a service and new belts fitted just after i bought it and it's been great.

 That said, it's recently started losing coolant, Is seems to be pooling in the Vee at the top of the engine.

Anyone else have this? Most of what I've seen seems to relate to the expansion tank, but that seems perfect.

No loss of power or overheating or sludge in the oil so I'm discounting head gaskets.

There's a lot of pipes etc in the way, I only saw the pool by removing the engine cover and using a torch to peek between all the pipes etc.

Any help appreciated.