308 High oil and coolant consumption

[brianb]

My wife's 07 reg Peugeot 308 1.6vvt has developed very high consumption levels over the last year, as it stands she's going through aproximately 1ltr of oil and a expansion bottle of coolant per 1000 miles

There is no obvious sign of leaks, she parks in the same spot on our drive each evening, there is no smoke on start up (or when moving for that matter) no residue on the backbox, no mayo on the dipstick or oil cap

Obviously I'm expecting the worse however surely they'd be signs?

Any other suggestions?