If you are thinking of the 19.15 Jmk-Lcy service on a Sunday you have to consider that this is often delayed
Search results for "Ba2220" | The BA Source and sometimes diverted to SEN. It’s a self purchase Gyros before you fly service, if in economy. I did enjoy the CE service booked with Avios, but I wouldn’t pay cash for it, unless I needed the TPs.