It's in the KLM timetable, believe it or not.
Well darn it! Doggon !!!! And other expletives deleted.
And there I was trying Skyscanner ... and all the dead ends possible. I did check (or thought I did) KLM to begin with but it would only say ONE STOP ... and nothing more.
A very big T H A N K Y O U for your help .... and education!! The simplest ways are the best ways!! And it must be my lucky day because ET's website is actually working for me today ... it's always hung up on me, and when I sent an email to the contact address, I got .................. 55 auto replies telling me that my query would be dealt with after 27 September .... and loads of machine code. Today I got a reply telling me what I'd already guessed ... no interlining of baggage between CDG and SXB. Seems ET don't want to belong to any of the major airline supporters clubs.......................