When Bymon had the NQY-LHR route twice daily route (early morning and an evening ) with the 50 seat Herald (taken over from BMA in 1977 who had used a 73 seat VC8) we at BMA LHR handled BC and both their evening and the morning NQY flights were always very busy with both interliners and businessmen -- plus plenty of connecting pax to the Isles of Scilly on the morning departure out of LHR
Seem to recall at weekends it was a more limited service as the Herald did JER charters iirc from MAN and SEN.
When BC got the new Dash 7 a lunchtime service from LHR was added that flew via EXT
A new LHR-NQY service I reckon will be very successful for whoever operates it - Amazing what comes around again!