The 1600 EDI-LHR is the last possible flight you could take to connect to the LHR-MAD on the A340, if that floats your boat (and you're happy to pay the money for CE). Looks for the 1545 return from MAD-LHR to also get it on the return.

Depends on whether you actually want to visit somewhere or do what FTers do... I've given an option for the latter!