I don't know why they'd ask for a boarding pass, as unlike the American Express Platinum/Centurion access benefit, Priority Pass lounge access does not require a same-day flight on the carrier operating the lounge. As long as you can get yourself to the club entrance, you can get in with a Priority Pass.

Yes, it is, at the CO President's Club. Terminal 6.

I use Priority Pass and get asked for a boarding pass most of the time. Once in a rare while, I only need to check in to a lounge with my Priority Pass card. I've never tried entering without a boarding pass. My very basic suspicion is that the airline clubs like the UA RCC, or CO PC ask as a standard procedure, as they are used to keeping track of gate info for their UA or CO members. In non-affiliated clubs, I have been asked for my boarding pass, and the attendant has given me notice that my flight is boarding soon. But I can't say for sure why I get asked for the boarding pass, and what would happen if I didn't have one.

I used to have PP and used clubs several times without traveling. Of course, YMMV.

boarding pass or Amex?
 

I have the highest level PP thru Plat Amex. I was asked for my boarding pass at one of the lounges at LHR (can't recall which one, T3, upstairs, pretty small, Iberia maybe?) recently and duly handed it over, but I thought afterwards that according to Amex, I needed only show my PP and Plat card. I wasn't asked to show the Amex at all.

I'm always asked for a BP in the UK.

I still do.
Well my PP is just fine, had it checked the other day. Doc said everything looked good. Will be a while before I have to pee in that cup again. Glad flying hasn't taken my PP away. :D

I really am glad I was not there when you showed your PP, disgusting. :eek:

You generally only need to show the PPass card; the AmEx is irrelevant at that point. Or, in lounges in the USA (DL/CO/NW/AA) you can show the AmEx and a BP for access the same as showing the PPass card.

Why would they care about boarding pass???

They don't need to, but many lounges are just so used to asking for it that they ask everyone. Even without one I'm sure access would be granted.

ServisAir Lounge in Terminal 3 @ Heathrow

Lounge asked for my Border pass and visibly checked the name on the boarding pass with that of the card.

in HKG they always ask for BP.

I've used priority pass around asia and every time i've been asked for my boarding pass, which they verify my name against.

Also it is often the case that lounge rules say you can only use the lounge for x hours, or x hours before your flight, so often they need to check when you flight is.

RCC denver on 6/6
Priority pass swiped on card reader with imprint and signature; no boarding pass