Just googled it and apparently the production of that episode was disaterous. Jason Lyndhurst and O' Sullivan were all ill which prevented it from being filmed in front of a live audience.
Without the audience, to quote the OFAH Story "John Sullivan was not happy with A Royal Flush, feeling that it seemed to show Del in a negative light. Where as Del was always seen to be a loveable rogue, in this there were some scenes where he came over as boorish and offensive. To Suliivan and every OFAH fan, it just wasn't the Del Boy Trotter they came to know and love."
Apparently it was still being edited (for transmission) a couple of hours before it was broadcast on christmas day.
Maybe Sullivan took out all the stuff he didn't like