Can anyone please advise if this is still available on arrival at BKK?  I remember reading about this service being withdrawn last year but I am uncertain if it was ever reinstated and if so, where/what to expect. Any up to date info much appreciated. 

I arrived two weeks ago and yes, it was still available.

 

It's not in the "old" place between the main arrival halls but instead is part of these same halls.  I came from the west side of the terminal (Concourses E/F/G) and when you arrive at the ramp go to the far side of it and there's an area roped off labelled "Priority".  Your boarding pass may be checked there.

 

At the top of the ramp go to your right and you'll see the auto gates and just beyond these are the manned priority gates.