Lounge Access in LHR
 

I am traveling on an award ticket on BA (1st class) from BOS to OSL and transit through LHR, where I have a 5 hour layover. the LHR/OSL is in econony. My question is - will I be able to access a lounge in LHR and take a shower between flights? I do have AS lounge membership (if that helps)

No (AS lounge doesn't help here), but if your profile is correct and you're a MVPG, then based on status you will get access to J lounges. Actually your F class inbound will also give you the ability to visit the lounge as the primary/higher lounge location. Granted the second segment is on BA.
https://www.alaskaair.com/content/mi...rtner-benefits

Thanks - thats what I was looking for - just could not find it !!

Yep. OneWorld policy on this is that an F/J inbound passenger gets lounge access before a Y connection as long as the connecting flight is still on a OW carrier.

Hi, you'll be able to use the Concorde Room...BA's "premium" lounge by showing your boarding pass for the transatlantic. BA has no domestic or European 1st class anyway. You can BA You First and book what is called a cabana in the Concored Room (ifrc you can do this as soon as you make your reservation but I could have that confused with booking the free spa treatments at something like 30 or 60 days out....just call You First and ask). The cabanas are small sort of private rooms with a day bed, free phones, television and a full bath. They're rather unique and some time on the BA forum will fill you in. Also you can get ;"room service" in the cabana for a meal from the dining room in the room proper. If I have more than about 3 hours to kill after a TATL I like to get a cabana just to shower and freshen up and, maybe, have a light meal and some wine while watching telly. If you don't want a cabana, you can book a shower at the spa entrance and use the facilities there...quite nice as well but just a shower room. The spa treatments are fun....you can two free and it takes maybe 30 minutes....they have those huge massage chairs so I like one of those with a facial...nice treat. The Concorde Room has a decent restaurant as well..of course, it's all free...all the booze, wine, other drinks, food, spa, etc. so take advantage!