The waste run in my new kitchen is very long, and hence the BCO insisted on
installing an AAV on the 40mm pipe. The plan is to fit it under the worktop
next to the kitchen sink.

My logic suggests that the AAV needs to be fitted above the highest possible
water level in the sink. IS this really the case? i.e. do I need to re-think
my plan?

PS: I seem to recall seeing this done is my proposed way before, but cannot
remember the details.