Discreet bag for D600 and a few primes

Any suggestions for a bag that will hold a D600 plus prime lens (100mm max)  and say 2 primes up to 100mm size?

I'm preferably looking for something along the lines of a 'day bag' which could also be carried onboard an aircraft along with a piece of 'legal' carry-on luggage. In other words small enough not to stir the ire at check-in or of the flight attendants.

In terms of the later I find many airlines are non-plussed by a seperate camera bag provided it's smallish and discreet. I suppose this is mainly due to being allowed a laptop bag/handbag as part of one's 'carry-on' in addition to the normal overhead luggage allowance.

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AJ
Carpe diem quam minimum credula postero