If you mean the tube-staff, I have never seen one outside the station. I have never had a problem with the plice though. Last year I stayed in London for school and I was at LHR almost once every 3 weeks. Never had a problem!

I tended to move away a bit from the station because you are looking into the sun. Just walk around a bit and you will find something nice. In the end I usually ended up in the residential area, near the aviation catering.