I think that was from the 1976 series and unfortunately I believe that's one of the series that's also missing from the official archives
If it is indeed the one where Sooty (and Harry) got an OBE, then it's 1976, Episode 1 and aired 6th October 1976.
This is the synopsis from the TV Times from that week:
Hats off! Show a bit of respect there! Sooty, OBE has graciously consented to return to your screens despite his recent honour. (Well, actually it was Harry Corbett who received the OBE), but the bear, not to be outfaced, has had a miniature medal and ribbon made, and now he expects Sweep to curtsey each time he passes.Hope this helps!