(I previously posted this in a different thread but have deleted it there separated it out as its own thread so those who know about this in particular will see it and might be able to answer the question.)

Will LY accept a through-checked (interlined) bag at LHR from AA in JFK automatically transferred T3>T1 by the airport to the airline?

Or will I need to collect it and recheck it at LHR myself? If so, when does LY's checkin counter at LHR start accepting bags for LY316 (dep 1420)?

I'd like to be able to leave the airport since I have a long connection rather than killing time at LHR (especially without lounge access).