Tapping noise when left idling on drivers side of engine

Recently purchased this F2 HSE auto with 34k on the clock. All appeared ok initially but have just noticed that if the engine is left to idling after a couple of minutes there is a knocking sound on the drivers side of the engine. Stops when engine is given a few revs and only seems to reappear on idle. Oil and fluid levels all ok.
Vehicle has full service history.
Any thoughts appreciated.

Harmonic balancer ( crank shaft pulley) worth checking

Thanks, will investigate further.
Quick visual inspection indicates all appears secure with no obvious play. Can you advise how to check this in a meaningful way please.

Not very familier with the Freelander, but if it's a manual, I've known failing DMF's to make noises like that.

Fortunately (or possibly not) its an automatic. Thanks anyway.

.is it drivers side of engine or car,get out of the car,if noise is from rear off side wheel arch,its full pump for fuel burning heater.

Under bonnet offside sounds like it is at the offside of engine as "fanatic"suggests just inboard of the pulley and belt.

Having spent today looking, listening and turning on and off various functions I believe that I have now narrowed the noise down to the air con, probably the condenser. Looks like a trip to Land Rover dealer.

Finally resolved the problem which required replacement of the air con compressor. It appears that although it had been checked 5000 miles ago it hadnt been used since and that lack of use is an issue which leads to failure. Moral of the tale turn on the air con regularly or it will fail!

Yeah, the seal dries out and you loose the gas.

'Use it or loose it'