Do you have any recommendations on a top-class certification/ course covering executive comms and strategic thinking?

We are currently working with "Think and Talk", with Paula Rincón. Also the IE (Instituto de Empresas - Spain) has a very good teacher. Regarding the topic of strategic thinking, several universities have it, some included in management programs, such as Harvard, Kellogg and Stanford.

You probably need to narrow down  more specifically  what area of strategy .   

The very top class courses  are Executive Education courses  at the  top MBA schools  so  LBS , Said Oxford , Harvard , all run  world class  strategic  courses . Most  of the strategy courses have a comms element .

In the UK If you are looking for a specific exec to develop comms skills with a more strategic approach then I can recommend Hult EF Release your change-makers | Hult EF Corporate Education  (its a colaboration between  Hult Business School , Ashridge  (I did their Org Consulting Post Grad very good)  and Education First )  They are more skills Centric  than  theory  if that makes sense