HD :
As the first ever commercial 747 flight was Pan Am from JFK arriving Heathrow 23 January 1970 (it was the aircraft later lost in the Tenerife collision) I would be surprised if there were any Heathrow 747 movements in 1969 at all.
Regarding the Islander, I seem to recall an item some years ago saying as it was approaching Gatwick the main runway was blocked by a disabled jet and it was landed on the taxiway. I always thought this must be a tall story, surely that would not be licenced for a scheduled service operation, regardless of the aircraft's performance.
Tony Merton-Jones' "British Independent Airlines" gives lots of detail about the Westward Islander operation. The aircraft operated to/from Plymouth each day and the shuttle was a fill-in, 6 return trips a day, block time 15 minutes. Start 25 June 1969, last op 22 Aug 1970, but for the final month they had subcontracted it out to Southend Air Taxis with - wait for it - a Piper Cherokee. I think that merits a
!!! Wonder what the reaction would be if I tried to file a flight plan for myself with my Cherokee today for the same journey !