At end Jan QR would not check my luggage through all the way PER-DOH-OSL-LHR (PER-OSL on QR and OSL-LHR on BA with 2 separate tickets) but just as far as OSL.
Last week on 18 April (after some discussion!) our luggage was booked through to LHR: CMB-DOH-OSL (on QR), then separate ticket (BA) OSL-LHR. What was a pleasant surprise was that we (me and Mrs fbrj) got an unexpected upgrade to CE on our RFS BA econ tickets!