whining noise 2700+ rpm

[goldsax]

recently been getting a whining/whirring noise form the engine above 2700 rpm.

1) the engine starts perfectly hot or cold without any chain rattle etc.
2) noise starts about 25mins into the drive, after the engine is up to temperature.
3) no noise when cold.
4) i can put the car into P and on revving the sound is the same whine

could it be oil pump? variator? timing chain?

i am have the timing belt replaced next week, any advice?
many thanks